Spectroscopic chemical analysis methods and apparatus

ABSTRACT

Spectroscopic chemical analysis methods and apparatus are disclosed which employ deep ultraviolet (e.g. in the 200 nm to 300 nm spectral range) electron beam pumped wide bandgap semiconductor lasers, incoherent wide bandgap semiconductor light emitting devices, and hollow cathode metal ion lasers to perform non-contact, non-invasive detection of unknown chemical analytes. These deep ultraviolet sources enable dramatic size, weight and power consumption reductions of chemical analysis instruments. In some embodiments, Raman spectroscopic detection methods and apparatus use ultra-narrow-band angle tuning filters, acousto-optic tuning filters, and temperature tuned filters to enable ultra-miniature analyzers for chemical identification. In some embodiments Raman analysis is conducted along with photoluminescence spectroscopy (i.e. fluorescence and/or phosphorescence spectroscopy) to provide high levels of sensitivity and specificity in the same instrument.

RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.15/909,176, filed on Mar. 1, 2018, which is a continuation of U.S.patent application Ser. No. 15/432,865, filed on Feb. 14, 2017, now U.S.Pat. No. 9,915,603, which is a continuation of U.S. patent applicationSer. No. 14/313,987, filed on Jun. 24, 2014, now U.S. Pat. No.9,568,418, which in turn is a continuation of U.S. patent applicationSer. No. 12/628,205, filed on Nov. 30, 2009, now U.S. Pat. No.8,759,791, which claims benefit of U.S. Patent Application No.61/118,591, filed on Nov. 28, 2008, and is a continuation-in-part ofU.S. patent application Ser. No. 12/545,772, filed Aug. 21, 2009, nowU.S. Pat. No. 8,395,770. Each of these applications is incorporatedherein by reference as if set forth in full herein.

This application is related to U.S. patent application Ser. No.12/399,743, filed Mar. 6, 2009, now U.S. Pat. No. 7,800,753; U.S. patentapplication Ser. No. 11/245,486, filed Oct. 5, 2005, now U.S. Pat. No.7,525,653; and U.S. Provisional Application No. 60/616,269, filed Oct.5, 2004. Each of these related applications is incorporated herein byreference as if set forth in full herein.

US GOVERNMENT RIGHTS

One or more of the inventions set forth herein were made with U.S.Government support under one or more of (1) NASA Contract No.NAS2-02085, (2) DARPA Contract No. W31 P4Q-04-C-R039, and/or (3) DTRAContract No. HDTRA1-09-C-0010. The Government has certain rights to theinvention.

FIELD OF THE INVENTION

This invention relates to non-contact spectroscopic methods andapparatus for performing chemical analysis and the ideal wavelengths andsources needed for this analysis. In some embodiments, for example, themethod can be used, in a microscope or macroscope to provide measurementof Raman and/or photoluminescence, (i.e. native fluorescence and/orphosphorescence) emission spectra and/or decay time characteristicseither by point-by-point measurement or by global imaging of emissionsand decay times within specific ultraviolet spectral bands. In otherembodiments, the method can be used in analytical instruments such ascapillary electrophoresis, capillary electrochromatography, highperformance liquid chromatography, flow cytometry, and relatedinstruments for detection and identification of unknown analytes using acombination of photoluminescence (i.e. native fluorescence and/orphosphorescence) and/or Raman spectroscopic methods. Further embodimentsof this invention use deep ultraviolet sources of radiation generated byelectron-beam-pumped, wide bandgap, semiconductor devices, that include,for example alloys and structures made from aluminum and galliumnitrides, diamond, or related materials.

BACKGROUND OF THE INVENTION

The use of optical sources of radiation such as lasers, light emittingdiodes (LED's), arc lamps, and other sources of incoherent radiation toperform chemical analysis and identification has been known for manyyears and such sources have been used in a wide range of chemicalanalysis and analytical instruments. Among these instruments, capillaryelectrophoresis, high performance liquid chromatography, flow cytometry,Raman and fluorescence microscopy and spectroscopy are emerging aspowerful analytical tools for a wide range of biological and chemicalresearch, as well as clinical, industrial, and governmentalapplications. These instrumental techniques are being increasingly usedin commercial and governmental applications such as product inspectionduring the manufacture of pharmaceutical and medical products,manufactured food and chemical products, environmental testing, andother applications.

When a sample is exposed to radiation (e.g. infrared (IR) radiation,visible light, or ultraviolet (UV) radiation) at a given frequency, someof the radiation is transmitted through the sample. Some of theradiation is elastically scattered and retains the same frequency as theincident radiation. Some of the radiation is absorbed in the sample. Theabsorbed radiation is either re-emitted after interaction with thesample or converted to thermal energy in the sample. The re-emittedradiation is sometimes referred to as inelastically scattered radiation.The inelastically scattered radiation is re-emitted as fluorescence orphosphorescence at wavelengths longer than, or frequencies shorter thanthe irradiation frequency, and a small fraction is re-emitted as Ramanscattered radiation. Fluorescence or phosphorescence emissions are redshifted from the excitation frequency and have a spectral distributionthat is relatively independent of the excitation frequency. Ramanemissions are dependent on excitation frequency and are measured as asum or difference frequency from the excitation frequency. Absorption ofradiation requires that the energy of the exciting photon is higher thanthe first excited state of the molecule being excited. Raman emissionscan be either blue (anti-Stokes) or red (Stokes) shifted from theexcitation frequency by an amount determined by the rotational andvibrational bonds within the molecules being irradiated. Ramanscattering efficiency is typically very low compared to fluorescence.However, when the energy of the excitation radiation corresponds tostrong absorption bands of the analyte, a resonance effect can amplifythe Raman signal by many orders of magnitude.

Fluorescence, phosphorescence and Raman techniques are employed forchemical detection and identification in a wide range of instruments.Lasers, LED's and other sources are typically used for excitation.Chemical separation technologies such as capillary electrophoresis (CE),high performance liquid chromatography (HPLC), capillaryelectrochromatography (CEC), and various related instrumental formsallow rapid separation of complex chemical and biochemical mixtures intocomponent elements. Laser induced fluorescence (LIF) allows thesensitive detection of separated elements or analytes where limits ofdetection have been demonstrated into the zeptomole range.

A major drawback to the use of fluorescence detection is that the vastmajority of chemicals do not absorb strongly at visible or infraredwavelengths where simple, inexpensive lasers emit. In order to match theemission wavelength of these desirable lasers and other sources,fluorescence detection performed above about 300 nm requiresderivatization of most analytes with a fluorescent dye tag prior toanalysis. This is highly inconvenient, especially at low analyteconcentrations, and for compounds that lack appropriate functionalgroups. For multifunctional compounds such as proteins, it is verydifficult to ensure stoichiometrical reactions that can result incomplex mixtures after derivatization. Derivatization limits the typesof molecules that can be studied, can lower overall detectionsensitivity, reduces the ability to find unexpected analytes in complexmixtures, and may alter the very chemistry being studied. Derivatizationis commonly employed in analytical instruments today because of the lackof suitable lasers in the deep UV with small size, reasonable powerconsumption, and acceptable cost. The sensitivity and specificity aswell as simplicity and ease of use of analytical instruments have beendemonstrated to be considerably enhanced when combined with a laser thatemits in the deep UV between 200 nm and 300 nm. These advantages weredemonstrated using lasers that are unacceptable in a commercialinstrument application because of their size, weight, power consumption,and/or cost. The advantages of deep UV excitation are true for detectionin chemical separation instruments as well as in point-by-point orglobal imaging instruments, and other instruments using optical methodsof detection. In addition to fluorescence, Raman spectroscopy is apowerful analytical method for determining properties of unknownmaterials. Narrow Raman emission bands carry a great deal moreinformation on molecular structure, in contrast to broadbandfluorescence emission. It has been hampered as an analytical method bythe fact that normal Raman scatter cross-sections of materials aretypically very small. Another problem that has hampered Ramanspectroscopy as an analytical method is fluorescence background frommany materials at wavelengths of interest in obtaining Raman spectra. Inthe visible portion of the spectrum where many types of lasers areavailable, many materials emit fluorescence that overwhelms the smallRaman emissions from a sample. To alleviate this problem instrumentshave been developed which operate in the near infrared wherefluorescence background is greatly diminished or, in some cases,eliminated. The problem remains that Raman scatter cross-sections in theinfrared are small and powerful lasers are needed to obtain Ramanspectral data. In addition to their other problems, these powerfullasers sometimes cause sample damage.

Several advantages arise for Raman spectroscopy and analysis when usinga deep ultraviolet laser to irradiate a sample. First, scattercross-sections are inversely proportional to the fourth power ofexcitation wavelength. Thus, as the excitation wavelength of a laser ismoved from the near infrared to the ultraviolet, an increase over 100times in Raman scattering typically occurs. Second, when excitationoccurs below about 250 nm, fluorescence background is eliminated withinthe Raman spectral range of most samples. This ubiquitous fluorescence,which is a major impediment for visible wavelength Raman studies, doesnot occur for UV spectral studies below about 270 nm. This is because atthese high energies the excited state of most molecules in a condensedphase relaxes by means of fast radiationless processes before it hastime to fluoresce. Third, when excitation occurs within an electronicabsorption band of the sample, a resonance effect causes dramaticincreases in Raman signal strength, often over one million to onehundred million times, thus eliminating the need for powerful lasers.Many types of materials have strong absorption bands in the deepultraviolet below about 300 nm. These include organic and biologicalmaterials as well as a large range of other materials. And fourth,resonance Raman bands are enhanced preferentially for those molecularbonds associated with the electronic absorption, thus considerablysimplifying the Raman spectra and making them more easily interpreted.For these types of samples, deep ultraviolet Raman spectroscopy andsingle band Raman imaging can be important analytical methods.

The state of the art of Raman spectroscopy can still be advanced by theapplication of additional deep UV laser sources to such analyticinstruments (particularly low power and/or small size sources), by usingoptical components that allow further reductions in system size, weight,power consumption, and the like.

Various analytic instruments and analytic methods have been describedpreviously. Patents having such teachings include:

-   -   1. U.S. Pat. No. 6,287,869, entitled “Analytic Instrument Using        a Sputtering Metal Ion Laser” by Hug, et al.;    -   2. U.S. Pat. No. 6,002,476, entitled “Chemical Imaging System”        by Treado;    -   3. U.S. Pat. No. 5,623,342, entitled “Raman Microscope” by        Batchelder, et. al.;    -   4. U.S. Pat. No. 5,442,438, entitled “Spectroscopic Apparatus        and Methods”, by Batchelder, et. al.; and    -   5 U.S. Pat. No. 5,194,912, entitled “Raman Analysis Apparatus”        by Batchelder, et. al.

The teachings of each of these patents are hereby incorporated herein byreference as if set forth in full. With the exception of the '869patent, a feature that universally distinguishes these patents from someembodiments of the invention is that they are related to apparatusutilizing visible or infrared wavelengths. The teachings of the '869patent will be discussed further herein after.

Additional publications providing teachings about analytic instrumentsand methods include:

-   -   1. Ianoul, A., T. Coleman, and S. A. Asher, “UV Resonance Raman        Spectroscopic Detection of Nitrate and Nitrite in Wastewater        Treatment Processes”, Anal. Chem., Vol. 74, pp. 1458-1461, 2002.    -   2. Storrie-Lombardi, M. C., W. F. Hug, G. D. McDonald, A. I.        Tsapin, and K. H. Nealson. “Hollow cathode ion laser for deep        ultraviolet Raman spectroscopy and fluorescence imaging”. Rev.        Sci. Instruments, 12, 4452-4459, December 2001    -   3. Sparrow, M. C., J. F. Jackovitz, C. H. Munro, W. F. Hug,        and S. A. Asher, “A New 224 nm Hollow Cathode UV Laser Raman        Spectrometer”, J. App. Spectroscopy, Vol. 55, No. 1, January        2001.    -   4. Gillespie, S. R. and J. W. Carnahan, “Ultraviolet Quartz        Acousto-optic Tunable Filter Wavelength Selection for        Inductively Coupled Plasma Atomic Emission Spectrometry”, J.        App. Spectroscopy, Vol. 55, No. 6, 2001.    -   5. Wu, Q, T. Hamilton, W. H. Nelson, S. Elliott, J. F. Sperry,        and M. Wu, “UV Raman Spectral Intensities of E. coli and Other        Bacteria Excited at 228.9, 244.0 and 248.2 nm”, Anal. Chem. Vol.        73, No. 14, pp. 3432-3440, Jul. 15, 2001    -   6. McCreery, R. L., “Raman Spectrocopy for Chemical Analysis”,        John Wiley & Sons, ISBN #0-471-25287-5, 2000.    -   7. Munro, C. H., V. Pajcini, and S. A. Asher, “Dielectric Stack        Filters for Ex Situ and In Situ UV Optical-Fiber Probe Raman        Spectroscopic Measurements”, App. Spect., Vol. 51, No. 11, pp        1722-1729, 1997.    -   8. Morris, H., C. et. al., “Liquid Crystal Tunable Filter Raman        Chemical Imaging”, App. Spect., Vol. 50, No. 6, pp. 805-811,        1996.    -   9. Turrell, G, et. al., “Raman Microscopy”, Academic Press Ltd.,        ISBN #0-12-189690-0, 1996.    -   10. Macleod, A., “Thin-Film Optical Filters”, McGraw-Hill, ISBN        #0-07-044694-6, reprinted 1989    -   11. Treado, P. J., and M. D. Morris, “A Thousand Points of        Light: The Hadamard Transform in Chemical Analysis and        Instrumentation”, Anal. Chem., Vol 61, No. 11, pp. 722-734, Jun.        1, 1989.    -   12. Asher, S. A., “Raman Spectroscopy of a Coal Liquid Shows        That Fluorescence Interference Is Minimized with Ultraviolet        Excitation”, Science, Vol. 225, 20 Jul. 1984.    -   13. Wolf, W. L. ed., Handbook of Military Infrared Technology,        Office of Naval Research, Dept. of the Navy, Washington, D.C.,        pp. 286-306, 1965.    -   14. Military Standardization Handbook, MIL-HDBK-141, Section 20,        5 Oct. 1962. (angle dependence, p. 20-11)    -   15. Jenkins, F. A. and H. E. White, Fundamentals of Optics,        (McGraw Hill), 1957.    -   16. Mooney, C. F., and A. F. Turner, “Infrared Transmitting        Interference Filters, Proceedings of the Conference on Infrared        Optical Materials, Filters, and Films”, Engineering Research and        Development Laboratories, Fort Belvoir, Va. (1955).

Each of the publications is hereby incorporated herein by reference asif set forth in full. Additional references having such teachings arefound in the background of previously incorporated U.S. Pat. No.6,287,869. These additional references are hereby incorporated thereinby reference as if set forth in full.

The teachings in U.S. Pat. No. 6,287,869 provided improved and morecommercially viable analytical systems by providing deep UV radiationsources in the form of sputtering metal ion hollow cathode lasers foruse in such systems. These lasers provided improved choice of emissionwavelengths, improved duty cycle, reduced size, reduced powerconsumption, reduced complexity, reduced cost and improved reliability.A need remains, however, for other UV radiation sources that providefurther size reductions, weight reductions and cost savings for use inanalytical instruments.

Semiconductor optical sources including lasers and light emitting diodesmay be the ultimate forms of radiation sources for analyticalinstruments since they typically are very small, have low powerconsumption and can be produced at low cost. Research on blue andultraviolet lasers has been ongoing for many years with significantprogress. But several major technical roadblocks have impeded progressin demonstrating sources which operate in the deep UV, especially atwavelengths less than about 300 nm. Wide bandgap semiconductor materialsbased on alloys of aluminum and gallium nitrides plus various dopantsare being extensively investigated to fulfill the need for UVsemiconductor sources. Pure aluminum nitride (AlN) has a bandgap of 6.2electron volts (eV), which corresponds to an emission wavelength of 200nm. Pure gallium nitride (GaN) has a bandgap of 3.4 electron volts,which corresponds to an emission wavelength of 365 nm. By alloying thesematerials any emission wavelength between 200 nm and 365 nm cantheoretically be produced. To produce a semiconductor laser withemission wavelength less than 250 nm requires an aluminum mole fractionin the alloy greater than about 60%. The major roadblocks to producingdeep UV semiconductor sources have been:

-   -   1. the inability to adequately p-dope AlGaN materials with        aluminum content greater than a few percent (i.e. measure as        mole fraction);    -   2. the inability to make low resistance, ohmic, contacts to        AlGaN alloys with aluminum content greater than a few percent;    -   3. Lattice mismatch with available substrate materials resulting        in high defect density in active region;    -   4. Inability to form facets with low losses at deep UV        wavelengths; and    -   5. Difficulty in forming waveguiding layers in high Al-content        AlGaN alloys.        A need exists in the art for overcoming these roadblocks. The        first two items above are the most significant of these        roadblocks.

The general idea of using electron beams to pump various materials toproduce laser output is not new. In fact, a significant amount ofliterature and some patents exist on various devices and applicationsbased on these methods. These publications date back to 1964. Thesepublications include the following articles and patents, each of whichis incorporated herein by reference:

-   -   1. C. E. Hurwitz and R. J. Keyes, “Electron-beam-pumped GaAs        Laser”, App. Phys. Lett, Vol. 5, No. 7, pp. 139-141, (Oct. 1,        1964).    -   2. C. E. Hurwitz, “Efficient ultraviolet laser emission in        e-beam excited ZnS”, Appl. Phys. Lett., v. 9, N. 3, pp 116-118        (1966)    -   3. C. E. Hurwitz, High Power and Efficiency in CdS Electron Beam        Pumped Lasers, Applied Physics Letters, vol. 9, No. 12, Dec. 15,        1966, pp. 420-423.    -   4. C. E. Hurwitz, “Electron-beam pumped lasers of CdSe and CdS”,        App. Phys. Lett., Vol. 8, No. 5, pp. 121-124, (March 1966)    -   5. C. E. Hurwitz, “Efficient visible lasers of CdSeSe by        electron-beam-excitation”, Applied Physics Letters 8, 243        (1966)].    -   6. C. A. Klein, “Further remarks on electron beam pumping of        laser materials”, Appl. Optics, 5, 12, 1922 (1966)    -   7. Nasibov et al., “Electron-Beam Tube with a Laser Screen”,        Sov. J. Quant. Electron., vol. 4, No. 3, September 1974, pp.        296-300.    -   8. O. V. Bogdankevich et al., Application of Electron Beam        Pumped Semiconductor Lasers to Projection Television, IEEE        Journal of Quantum Electronics, vol. 13, No. 9 (September        1977), p. 65D.    -   9. O. V. Bogdankevich, The Use of Electron-Beam Pumped        Semiconductor Lasers in Projection Television, IEEE Journal of        Quantum Electronics, vol. QE-14, No. 2, February 1978, pp.        133-135.    -   10. Bogdankevich et al., “Multilayer GaAs—AlAs Heterostructure        Laser Pumped Transversely by an Electron Beam”, Sov. J. Quantum        Electron. 10 (6), June 1980, pp. 693-695.    -   11. Bogdankevich et al., “Influence of Doping of Ga.sub.0.68        Al.sub.0.32 As on its Cathodoluminescence and Threshold Current        Density of a Laser Pumped by an Electron Beam”, Sov. J. Quant.        Electron., 11 (1), January 1981, pp. 119-121.    -   12. B. Kozlovskii, A. Nasibov, et. al., Sov. J. Quant. Electr.,        12, 505 (1982)    -   13. E. Markov, V. Smirnov, V. Khryapov, “Physics and technical        application AB Semiconductors”, V Conf., Prod., Vilnius, S U, 3,        131 (1983)    -   14. O. V. Bogdankevich et al., Distribution of the excitation        density in electron-beam-pumped semiconductor lasers, Sov. J.        Quantum Electron. 13 (11), November 1983, pp. 1453-1459.    -   15. Tong, F., R. M. Osgood, A. Sanchez, and V. Daneu,        “Electron-beam-pumped two-dimensional laser array with tilted        mirror resonator”, App. Phys. Letters (ISSN00003-6951), Vol. 52,        pp. 1303-1305, Apr. 18, 1988    -   16. I. Akimova, V. Kozlovskii, et. al, “The influence of        stoichiometry in A2B6 monocrystal compounds on the        characteristics of a semiconductor electron-beam pumped laser”,        Proc. Of Lebedev Phys. Inst., Nova Science Publ., USA, v. 177,        pp. 195-233, 1988.    -   17. A. Nasibov, V. Kozlovsky, Y. Skasyrsky, “Deep blue and        ultraviolet e-beam pumped semiconductor lasers”, SPIE Vol. 1041,        Metal Vapor Deep Blue and Ultraviolet Lasers, Los Angeles,        Calif., 17-20 Jan. 1989.    -   18. Molva, E., R. Accomo, G. Labrunie, J. Cibert, C. Bodin, Le        Si Dang, and G. Feuillet, “Microgun-pumped semiconductor laser”,        App. Phys. Letters, Vol. 62(8), pp. 796-798, Feb. 22, 1993    -   19. O. V. Bogdankevich, “Electron-beam-pumped semiconductor        lasers”, Quantum Electronics, Vol 24, No. 12, pp. 1031-1053,        1994.    -   20. D. Herve, R. Accomo, E. Molva, L. Vanzetti, J. J. Paggel, L.        Sorba, and A. Francoisi, “Microgun-pumped blue lasers”, App.        Phys. Letters, Vol. 67(15), pp. 2144-2146, Oct. 9, 1995    -   21. V. I. Kozlovshy, A. B. Krysa, Y. K. Skyasyrsky, Y. M.        Popov, w. S. DenBaars, “Electron beam pumped MQW InGaN/GaN        laser”, MRS Internet J. Nitride Semicond. Res. 2, 38 (1997).    -   22. J. M. Bonard, J. D. Ganiere, L. Vanzetti, et. al.,        “Transmission electron microscopy and cathodoluminescence        studies of extended defects in electron-beam-pumped        Zn_(1−x)Cd_(x)Se/ZnSe blue-green lasers”, J. App. Phys., (83) 4        p 1945 (15 Feb. 1998)    -   23. S. Krivoshlykov, “Compact high-efficiency        electron-beam-pumped semiconductor laser operating at room        temperature”, BMDO Phase I SBIR 1999    -   24. Nicholls, J. E., B. Lunn, et. al., “Electron-beam-pumped        near-UV semiconductor laser emission”, EPSRC reference number        GR/L27206, University of Hull, UK.    -   25. J. R. Packard, et. al., “Electron Beam Laser”, U.S. Pat. No.        3,757,250, Sep. 4, 1973    -   26. R. R. Rice, et. al., “Vertical cavity electron beam pumped        semiconductor lasers and methods”, U.S. Pat. No. 5,807,764, Sep.        15, 1998    -   27. R. R. Rice, et. al., “Vertical cavity electron beam pumped        semiconductor lasers and methods”, U.S. Pat. No. 5,677,923, Oct.        14, 1997.    -   28. D. A. Campbell, et. al., “Zinc Oxide Laser”, U.S. Pat. No.        3,505,613, Apr. 7, 1970.

A need exist in the field for extending the use of electron beam pumpingto additional materials and applications so as to enable improvedradiation sources (e.g. lasers and incoherent sources) which in turn mayenable improved applications for such sources, e.g. improved chemicalanalysis methods and devices.

SUMMARY OF THE INVENTION

It is an object of some embodiments of the invention to provide animproved Raman analysis method and/or an improved photoluminescenceanalysis method (i.e. an improved native fluorescence analysis method,and/or an improved phosphorescence analysis method).

It is an object of some embodiments of the invention to provide ananalytic method or apparatus requiring or having reduced size (e.g. asize under 20 liters).

It is an object of some embodiments of the invention to provide ananalytic method or apparatus requiring or having reduced weight (e.g. aweight under 100 pounds).

It is an object of some embodiments of the invention to provide ananalytic method or apparatus requiring or having reduced powerconsumption (e.g. power consumption under 100 watts).

It is an object of some embodiments of the invention to provide anelectron-beam-pumped semiconductor radiation producing method or sourcethat can emit at a wavelength or wavelengths below 300 nm, e.g. in thedeep ultraviolet between about 200 nm and 300 nm, and more preferablyless than about 260 nm. In some variations of this objective the methodor source is to produce incoherent radiation while in otherimplementations it produces laser radiation. In some variations, thisobject is achieved, for example, using a aluminum gallium nitride(ALGaN) emission medium while in other implementations a diamondemission medium may be used

It is an object of some embodiments of the invention to provide ananalytic method or instrument that irradiates a sample with deep UVradiation and uses an improved filter for separating wavelengths to bedetected.

It is an object of some embodiments of the invention to provide a methodor apparatus that provides multi-stage analysis of a sample where thestages may be separated by different wavelength ranges, detection ofdifferent types of inelastically scattered radiation (e.g. Raman,fluorescence, phosphorescence), and/or detection at different timesrelative to application of excitation radiation.

Other objects and advantages of various aspects of the invention will beapparent to those of skill in the art upon review of the teachingsherein. The various aspects of the invention, set forth explicitlyherein or otherwise ascertained from the teachings herein, may addressany one of the above objects alone or in combination, or alternativelymay address some other object of the invention ascertained from theteachings herein. It is not intended that any specific aspect of theinvention (that is explicitly set forth below or that is ascertainedfrom the teachings herein) necessarily address any of the objects setforth above let alone address all of these objects simultaneously, butsome aspects may address one or more of these objects or even all ofthese objects simultaneously.

In a first aspect of the invention a method of providing a chemicalanalysis of a sample includes: supplying a sample to be analyzed;applying excitation radiation from a semiconductor source having awavelength less than about 300 nm directly or indirectly onto thesample; receiving emission radiation, directly or indirectly, from thesample at a spectral filter which is capable of passing a selected rangeof wavelengths of the emission radiation along a given optical path;measuring an amount of the selected emission radiation present, using adetector located directly or indirectly along the selected optical path;correlating information concerning the amount of selected emissionradiation measured by the detector with data associated with one or morechemical compounds of interest to provide at least a partial chemicalanalysis of the sample.

In a second aspect of the invention a method of providing a chemicalanalysis of a sample includes: supplying a sample to be analyzed;applying radiation from an electron beam pumped semiconductor lightemitting device directly or indirectly onto the sample; receivingemission radiation, directly or indirectly, from the sample at aspectral filter which is capable of passing a selected range ofwavelengths of the emission radiation along a given optical path;measuring an amount of the selected emission radiation present, using adetector located directly or indirectly along the selected optical path;and correlating information concerning the amount of selected emissionradiation measured by the detector with data associated with one or morechemical compounds of interest to provide at least a partial chemicalanalysis of the sample.

In a third aspect of the invention a method of providing integratedchemical analysis of a sample includes: supplying a sample to beanalyzed; applying excitation radiation directly or indirectly onto thesample; receiving emission radiation, directly or indirectly, from thesample at a 1^(st) spectral filter which is capable of passing a 1^(st)selected emission radiation along a 1^(st) optical path; receivingemission radiation, directly or indirectly, from the sample at a 2^(nd)spectral filter which is capable of passing a 2^(nd) selected emissionradiation along a 2^(nd) optical path; measuring an amount of the 1^(st)selected emission radiation present using a 1^(st) detector locateddirectly or indirectly along the 1^(st) optical path; correlatinginformation concerning the amount of selected emission radiationmeasured by the 1^(st) detector with data associated with one or morechemical compounds of interest to provide at least a partial 1^(st)chemical analysis of the sample; measuring an amount of the 2^(nd)selected emission radiation using a 2^(nd) detector located directly orindirectly along the 2^(nd) optical path; and correlating informationconcerning the amount of 2^(nd) selected emission radiation measured bythe 2^(nd) detector with data associated with one or more chemicalcompounds of interest to provide at least a partial 2^(nd) chemicalanalysis of the sample.

In a fourth aspect of the invention a method of providing a chemicalanalysis of a sample, includes: supplying a sample to be analyzed,applying UV laser radiation directly or indirectly onto the sample;receiving radiation, directly or indirectly, from the sample at atunable spectral filter which is capable of passing a selected radiationalong a given optical path; measuring an amount of the selectedradiation present using a detector located directly or indirectly alongthe selected optical path; and correlating information concerning theamount of radiation measured by the detector with data associated withone or more chemical compounds of interest to provide at least a partialchemical analysis of the sample.

In a fifth aspect of the invention a method of providing a chemicalanalysis of a sample, includes: (a) supplying a sample to be analyzed;(b) applying ultraviolet excitation radiation from a source directly orindirectly onto the sample to produce emission radiation in the form ofRaman emission radiation within a first range of wavelengths andphotoluminescence emission radiation within a second range ofwavelengths; (c) receiving the emission radiation, directly orindirectly, from the sample at at least one first spectral filter whichis capable of passing the Raman emission radiation within at least aportion of the first range of wavelengths along a first optical path;(d) receiving the emission radiation, directly or indirectly, from thesample at at least one second spectral filter which is capable ofpassing the photoluminescence emission radiation within at least aportion of the second range of wavelengths along a second optical path;(e) measuring an amount of the Raman emission radiation using at leastone first detector located directly or indirectly along the firstoptical path; (f) measuring an amount of the photoluminescence emissionradiation using at least one second detector located directly orindirectly along the second optical path; and (g) correlatinginformation concerning the amounts of the Raman emission radiation andphotoluminescence emission radiation measured by the at least one firstdetector and the at least one second detector, respectively, with dataassociated with one or more chemical compounds of interest to provide atleast a partial chemical analysis of the sample.

Numerous variations of the fifth aspect of the invention are possibleand include, for example, one or more of: (1) the photoluminescenceemission radiation including fluorescence emission radiation,phosphorescence emission radiation, or both; (2) measuring thefluorescence and phosphorescence emission radiation at different timeswhen both are in the photoluminescence emission radiation; (3) thesource being selected from the group consisting of: (a) a semiconductorsource, (b) a an electron beam pumped semiconductor laser; (c) anelectron beam pumped incoherent semiconductor source; and (d) anelectron beam pumped AlGaN source; and (e) a hollow cathode laser; (4)the excitation radiation having a wavelength selected from the groupconsisting of (a) a wavelength less than 300 nm and (b) a wavelengthless than about 250 nm; (5) at least one of the at least one firstspectral filter or at least one second spectral filter including aselected filter chosen from the group consisting of (a) a tunablefilter; (b) a dispersive device; an acousto-optic tunable filter; atemperature tunable filter; (6) the chemical analysis being performed inconjunction with one or more sample handling or separation methodsselected from the group consisting of: (a) capillary electrophoresis(CE), (b) capillary electrochromatography (CEC), (c) high performanceliquid chromatography (HPLC), (d) microcapillary HPLC, (e) flowcytometry, (f) liquid flow cell methods, (g) air flow cell methods, and(h) a surface detection method; (7) the selected filter of the fifthvariation of the fifth aspect of the invention including an angletunable filter wherein the orientation of the angle tunable filter, withrespect to received emission radiation, is adjustable so as to enablethe Raman emission radiation or the photoluminescence radiation thatreaches the at least one first detector or the at least one seconddetector, respectively, to vary in wavelength and optionally wherein thereceiving and measuring operations occur multiple times with the atleast one tunable filter tuned to different wavelengths so as to obtaindata for a plurality of measurements for a plurality of wavelengths,wherein the correlating comprises determining relative amounts of themeasurements for at least two different wavelengths of the plurality ofwavelengths and comparing the relative amounts with the data; (8) themeasuring of the amount of the Raman emission radiation and themeasuring of the amount of the photoluminescence emission radiationoccur simultaneously; (9) the measuring of the amount of the Ramanemission radiation and measuring of the amount of the photoluminescenceemission radiation occur at different times; and/or (10) the measuringof the amount of an emission radiation selected from the groupconsisting of the Raman emission radiation and the photoluminescenceemission radiation is repeated multiple times and optionally at leastone of the repeated measurings occur after irradiation of the sample hasended. Further variations are also possible and include various mixturesof the above noted variations so long as such mixtures maintain thefunctionality of the method as a whole.

In a sixth aspect of the invention a method of providing a chemicalanalysis of a sample, includes: (a) supplying a sample to be analyzed;(b) applying ultraviolet excitation radiation from a source directly orindirectly onto the sample to produce emission radiation in the form ofphotoluminescence emission radiation within a first range ofwavelengths; (c) receiving the emission radiation, directly orindirectly, from the sample at at least one first spectral filter whichis capable of passing the photoluminescence emission radiation within atleast a portion of the first range of wavelengths along a first opticalpath; (d) measuring an amount of the photoluminescence emissionradiation using at least one first detector located directly orindirectly along the first optical path; and (e) correlating informationconcerning the amounts of the photoluminescence emission radiationmeasured by the at least one first detector with data associated withone or more chemical compounds of interest to provide at least a partialchemical analysis of the sample.

Numerous variations of the sixth aspect of the invention are possibleand include, for example, one or more of: (1) the photoluminescenceemission radiation including fluorescence emission radiation; (2) thephotoluminescence emission radiation including phosphorescence emissionradiation; (3) the photoluminescence emission radiation including bothfluorescence and phosphorescence emission radiation which are eachmeasured by the at least one first detector at difference times; (4) theadditional steps of (f) receiving photoluminescence emission radiation,directly or indirectly, from the sample at at least one second spectralfilter which is capable of passing photoluminescence emission radiationwithin a second range of wavelengths, which is different from the firstrange of wavelengths, along a second optical path; (g) measuring anamount of the photoluminescence emission radiation within the secondrange of wavelengths using at least one second detector located directlyor indirectly along the second optical path; and (h) correlatinginformation concerning the amount of photoluminescence emissionradiation within the second range of wavelengths measured by the atleast one second detector with data associated with one or more chemicalcompounds of interest to provide at least partial chemical analysis ofthe sample; (5) the at least portion of the first range of wavelengths,of the fourth variation of the sixth aspect of the invention,corresponds to fluorescence emission radiation and the at least portionof the second range of wavelengths corresponds to phosphorescenceemission radiation; (6) the additional steps of (f) receiving Ramanemission radiation, directly or indirectly, from the sample at at leastone second spectral filter which is capable of passing Raman emissionradiation within a second range of wavelengths, which is different fromthe first range of wavelengths, along a second optical path; (g)measuring an amount of the Raman emission radiation within the secondrange of wavelengths using at least one second detector located directlyor indirectly along the second optical path; (h) correlating informationconcerning the amount of Raman emission radiation within the secondrange of wavelengths measured by the at least one second detector withdata associated with one or more chemical compounds of interest toprovide at least partial chemical analysis of the sample; (7) the sourcebeing selected from the group consisting of: (a) a semiconductor source,(b) a an electron beam pumped semiconductor laser; (c) an electron beampumped incoherent semiconductor source; and (d) an electron beam pumpedAlGaN source; and (e) a hollow cathode laser; (8) the excitationradiation having a wavelength selected from the group consisting of (1)a wavelength less than 300 nm and (2) a wavelength less than about 250nm; (9) at least one of the at least one first spectral filter or atleast one second spectral filter, of the fourth variation of the sixthaspect of the invention, including a selected filter chosen from thegroup consisting of (a) a tunable filter; (b) a dispersive device; anacousto-optic tunable filter; a temperature tunable filter; (10) thechemical analysis is performed in conjunction with one or more samplehandling or separation methods selected from the group consisting of:(1) capillary electrophoresis (CE), (2) capillary electrochromatography(CEC), (3) high performance liquid chromatography (HPLC), (4)microcapillary HPLC, (5) flow cytometry, (6) liquid flow cell methods,(7) air flow cell methods, and (8) a surface detection method; (11) aselected one of the at least one first spectral filter includes at leastone angle tunable filter and the orientation of the at least one angletunable filter, with respect to received emission radiation, isadjustable so as to enable the photoluminescence emission radiation thatreaches the selected one of the at least one first detector to vary inwavelength; and (12) repeating the receiving and measuring operations,of the eleventh variation of the sixth aspect of the invention, with theat least one tunable filter tuned to different wavelengths so as toobtain data for a plurality of measurements for a plurality ofwavelengths, wherein the correlating comprises determining relativeamounts of the measurements for at least two different wavelengths ofthe plurality of wavelengths and comparing the relative amounts with thedata. Further variations are also possible and include various mixturesof the above noted variations so long as such mixtures maintain thefunctionality of the method as a whole.

In a seventh aspect of the invention a chemical analysis apparatusincludes: means for supplying a sample to be analyzed; means forapplying excitation radiation from a semiconductor source having awavelength less than about 300 nm directly or indirectly onto thesample; means for receiving emission radiation, directly or indirectly,from the sample at a spectral filter which is capable of passing aselected range of wavelengths of the emission radiation along a givenoptical path; means for measuring an amount of the selected emissionradiation present using a detector located directly or indirectly alongthe selected optical path; means for correlating information concerningthe amount of selected emission radiation measured by the detector withdata associated with one or more chemical compounds of interest toprovide at least a partial chemical analysis of the sample.

In an eighth aspect of the invention an apparatus for providing achemical analysis of a sample includes: means for supplying a sample tobe analyzed; means for applying radiation from an electron beam pumpedsemiconductor light emitting device directly or indirectly onto thesample; means for receiving emission radiation, directly or indirectly,from the sample at a spectral filter which is capable of passing aselected range of wavelengths of the emission radiation along a givenoptical path; means for measuring an amount of the selected emissionradiation present, using a detector located directly or indirectly alongthe selected optical path; and means for correlating informationconcerning the amount of selected emission radiation measured by thedetector with data associated with one or more chemical compounds ofinterest to provide at least a partial chemical analysis of the sample.

In a ninth aspect of the invention an apparatus for providing integratedchemical analysis of a sample includes: means for supplying a sample tobe analyzed; means for applying excitation radiation directly orindirectly onto the sample; means for receiving emission radiation,directly or indirectly, from the sample at a 1^(st) spectral filterwhich is capable of passing a 1^(st) selected emission radiation along a1^(st) optical path; means for receiving emission radiation, directly orindirectly, from the sample at a 2^(nd) spectral filter which is capableof passing a 2^(nd) selected emission radiation along a 2^(nd) opticalpath; means for measuring an amount of the 1^(st) selected emissionradiation present using a 1^(st) detector located directly or indirectlyalong the 1^(st) optical path; means for correlating informationconcerning the amount of selected emission radiation measured by the1^(st) detector with data associated with one or more chemical compoundsof interest to provide at least a partial 1^(st) chemical analysis ofthe sample; means for measuring an amount of the 2^(nd) selectedemission radiation using a 2^(nd) detector located directly orindirectly along the 2^(nd) optical path; and means for correlatinginformation concerning the amount of 2^(nd) selected emission radiationmeasured by the 2^(nd) detector with data associated with one or morechemical compounds of interest to provide at least a partial 2^(nd)chemical analysis of the sample

In a tenth aspect of the invention an apparatus for providing a chemicalanalysis of a sample, includes: means for supplying a sample to beanalyzed, means for applying UV radiation directly or indirectly ontothe sample; means for receiving radiation, directly or indirectly, fromthe sample at a tunable spectral filter which is capable of passing aselected radiation along a given optical path; detector means formeasuring an amount of the selected radiation present which is locateddirectly or indirectly along the selected optical path; and means forcorrelating information concerning the amount of radiation measured bythe detector with data associated with one or more chemical compounds ofinterest to provide at least a partial chemical analysis of the sample.

In an eleventh aspect of the invention an apparatus for providing achemical analysis of a sample, includes: (a) means for applyingultraviolet excitation radiation from a source directly or indirectlyonto the sample to produce emission radiation in the form of Ramanemission radiation within a first range of wavelengths andphotoluminescence emission radiation within a second range ofwavelengths; (b) first spectral filter means for receiving the emissionradiation, directly or indirectly, from the sample and for passing theRaman emission radiation within at least a portion of the first range ofwavelengths along a first optical path; (c) second spectral filter meansfor receiving the emission radiation, directly or indirectly, from thesample and for passing the photoluminescence emission radiation withinat least a portion of the second range of wavelengths along a secondoptical path; (d) first measuring means for detecting an amount of theRaman emission radiation which is located directly or indirectly alongthe first optical path; (e) second measuring means for detecting anamount of the photoluminescence emission radiation located directly orindirectly along the second optical path; and (f) means for correlatinginformation concerning the amounts of the Raman emission radiation andphotoluminescence emission radiation measured by the first and secondmeasuring means, respectively, with data associated with one or morechemical compounds of interest to provide at least a partial chemicalanalysis of the sample.

Variations of the eleventh aspect of the invention are possible andinclude functional counterparts and means plus function equivalents tothose variations noted above for the fifth aspect of the invention

In a twelfth aspect of the invention an apparatus for providing achemical analysis of a sample, includes: (a) a source means for applyingultraviolet excitation radiation directly or indirectly onto the sampleto produce emission radiation in the form of photoluminescence emissionradiation within a first range of wavelengths; (b) a first spectralfilter means for receiving the emission radiation, directly orindirectly, from the sample and for passing the photoluminescenceemission radiation, within at least a portion of the first range ofwavelengths, along a first optical path; (c) a first detector means formeasuring an amount of the photoluminescence emission radiation locateddirectly or indirectly along the first optical path; and (d) means forcorrelating information concerning the amounts of the photoluminescenceemission radiation measured by the first means for detecting with dataassociated with one or more chemical compounds of interest to provide atleast a partial chemical analysis of the sample.

Variations of the twelfth aspect of the invention are possible andinclude functional counterparts and means plus function equivalents tothose variations noted above for the sixth aspect of the invention.

In a thirteenth aspect of the invention an apparatus for providing achemical analysis of a sample includes: a window through which a sampleto be analyzed can be irradiated; a semiconductor source capable ofproducing radiation having a wavelength less than about 300 nm andoptically configured to direct radiation on to the window, a tunablefilter located along an optical path which is capable of receivingemission radiation from a sample and for passing selected radiation, asensor located on an optical path that extends from the tunable filterand is capable of providing an output indicative of the amount ofselected radiation present; an electronic device capable of receivinginput concerning the presence of selected radiation and to provide atleast a partial chemical analysis of the sample.

In a fourteenth aspect of the invention an apparatus for providing achemical analysis of a sample includes: an electron beam pumpedsemiconductor radiation emitting device; a spectral filter, a radiationsensor, an optical path extending from the radiation emitting device toa sample to be analyzed to the spectral filter and to the sensor, anelectronic comparator electrically connected to the radiation sensor andto information about one or more chemical compounds of interest.

In a fifteenth aspect of the invention an apparatus for providingintegrated chemical analysis of a sample includes: a source of narrowband radiation (e.g. ultraviolet radiation having a wavelength under 300nm, more preferably under 280 nm, and even more preferably having awavelength under 250 nm, and having a bandwidth less than 200wavenumbers and more preferably less than 100 wavenumbers); a 1^(st)spectral filter; a 2^(nd) spectral filter; a 1^(st) radiation detector;a 2^(nd) radiation detector; a source of electronic data (e.g. anelectronic storage device such as RAM, ROM, flash memory, a hard disk,internet connection, or the like) concerning one or more chemicalcompounds of interest, at least one electronic comparator (e.g. acomputer programmed to compare stored data to measured data andpotentially to derive conclusions based on the comparison); an initialoptical path that directs, directly or indirectly, narrow band radiationfrom the source onto a sample to be analyzed; a 1^(st) optical path thatdirects, directly or indirectly, emission radiation from the sample tothe 1^(st) spectral filter and then directs, directly or indirectly,1^(st) selected radiation to the 1^(st) radiation detector; a 2^(nd)optical path that directs, directly or indirectly, emission radiationfrom the sample to the 2^(nd) spectral filter and then directs, directlyor indirectly, the 2^(nd) selected radiation to the 2^(nd) radiationdetector; a 1^(st) communication path that carries information from the1^(st) detector to the at least one electronic comparator; a 2^(nd)communication path that carries information from the 2^(nd) detector tothe at least one electronic comparator.

In a sixteenth aspect of the invention an apparatus for providing achemical analysis of a sample includes: a UV laser; a tunable spectralfilter for passing selected radiation; a radiation detector, anelectronic data storage device, an electronic comparator for comparingstored data to measured data; an initial optical path that directs,directly or indirectly, radiation from the UV laser to a sample to beanalyzed; a 1^(st) optical path that directs, directly or indirectly,emission radiation from the sample to the spectral filter and thendirects, directly or indirectly, selected radiation to the radiationdetector; a communication path that carries, directly or indirectly,information from the radiation detector to the electronic comparator.

In a seventeenth aspect of the invention an apparatus for providing achemical analysis of a sample, includes: (a) a source of ultravioletexcitation radiation configured to direct the radiation on to a sampleto be analyzed wherein the sample is capable of producing Raman emissionradiation within a first range of wavelengths and photoluminescenceemission radiation within a second range of wavelengths; (b) a firstspectral filter configured to direct Raman emission radiation within atleast a portion of the first range of wavelengths along a first opticalpath; (c) a second spectral filter configured to directphotoluminescence emission radiation within at least a portion of thesecond range of wavelengths along a second optical path; (d) a firstdetector located on the first optical path; (e) a second detectorlocated on the second optical path; and (g) a computational deviceconfigured to correlate information concerning the amounts of the Ramanemission radiation and photoluminescence emission radiation measured bythe first and second detectors, respectively, with data associated withone or more chemical compounds of interest to provide at least a partialchemical analysis of the sample.

Variations of the seventeenth aspect of the invention are possible andinclude functional counterparts and means plus function equivalents tothose variations noted above for the fifth aspect of the invention.

In an eighteenth aspect of the invention an apparatus for providing achemical analysis of a sample, includes: (a) a source of ultravioletexcitation radiation configured to direct the excitation radiation ontoa sample to produce emission radiation in the form of photoluminescenceemission radiation within a first range of wavelengths; (b a firstspectral filter configured to receive the emission radiation and forpassing the photoluminescence emission radiation, within at least aportion of the first range of wavelengths, along a first optical path;(c) a first detector located on the first optical path configured toreceive and measure an amount of the photoluminescence emissionradiation; and (e) a computational device configured to correlateinformation concerning the amounts of the photoluminescence emissionradiation measured by the first detector with data associated with oneor more chemical compounds of interest to provide at least a partialchemical analysis of the sample.

Variations of the eighteenth aspect of the invention are possible andinclude functional counterparts and means plus function equivalents tothose variations noted above for the sixth aspect of the invention.

Numerous additional variations of the first—eighteenth aspects of theinvention are possible and include for example, mutatis mutandis, thosevariations specifically noted above for the fifth and sixth aspects ofthe inventions to the extent they apply to the other aspects withouteliminating their functionality. For example, some variations of thefirst to third, seventh to tenth, and thirteenth to fifteenth aspects ofthe invention may include excitation radiation being applied from asource in the form of a semiconductor laser. In other variations, theexcitation radiation may be supplied from an incoherent semiconductorsource.

Further aspects of the invention will be understood by those of skill inthe art upon reviewing the teachings herein. These other aspects of theinvention may provide various combinations of the aspects presentedabove as well as provide other configurations, structures, functionalrelationships, and processes that have not been specifically set forthabove.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 provides a plot of band gap emission in nanometers versus molefraction X of Al in Al_(X) Ga_(1−X)N.

FIG. 2 provides a schematic cut view of an incoherent radiationproducing electron-beam-pumped light emitting triode (ELET) deviceaccording to a first embodiment of the invention.

FIG. 3 provides a schematic cut view of an electron-beam-pumped verticalcavity surface emitting laser (EVCSEL) device according to a secondembodiment of the invention.

FIG. 4A provides a perspective view of an electron-beam-pumped edgeemitting laser (EEEL) device according to a third embodiment of theinvention.

FIGS. 4B and 4C provide schematic cut views of an electron-beam-pumpededge emitting laser (EEEL) device according to a fourth embodiment ofthe invention where the cuts are taken along two perpendicular axes.

FIGS. 5A-5F provide schematic depictions of various states in a processof forming a semiconductor laser according to some embodiments of theinvention.

FIG. 6A provides a simplified block diagram of components of a chemicalanalysis system according to a first class of analytical instrumentembodiments of the invention.

FIG. 6B provides a block diagram illustrating examples of various typesof analysis that the spectral filters can be tailored to provide.

FIG. 6C provides a block diagram illustrating examples of differenttypes of spectral filters that may be used in conjunction with the firstclass of analytical instrument embodiments.

FIG. 6D provides a block diagram illustrating examples of differenttypes of detectors that may be used in accordance with the first classof analytical instrument embodiments.

FIG. 6E provides a block diagram illustrating examples of differenttarget forms in which the sample may be provided.

FIG. 6F provides a block diagram illustrating examples of environmentalconditions under which sampling may be performed.

FIG. 7A provides a more detailed block diagram of components of achemical analysis system according some embodiments in the first classof analytical instrument embodiments.

FIG. 7B provides a block diagram illustrating various examples ofoutputs associated with some chemical analysis systems of some of theembodiments of the first class of analytical instrument embodiments.

FIG. 8A provides a simplified block diagram of components of a chemicalanalysis system according to a second class of analytical instrumentembodiments of the invention.

FIG. 8B provides a block diagram illustrating examples of differenttypes of radiation sources that may be used in conjunction with thesecond class of analytical instrument embodiments.

FIG. 8C provides a block diagram illustrating examples of differenttypes of tunable filters that may be used in conjunction with the secondclass of analytical instrument embodiments.

FIG. 9A provides a block diagram of components of a chemical analysissystem according to a third class of analytical instrument embodimentsof the invention.

FIG. 9B provides a block diagram of components of a chemical analysissystem according to a fourth class of analytical instrument embodimentsof the invention.

FIG. 9C provides a block diagram of components of a chemical analysissystem according to a fifth class of analytical instrument embodimentsof the invention.

FIG. 10A provides a block diagram of a chemical analyzer packageaccording to some embodiments of the invention where the packageincludes a power supply and a controller.

FIG. 10B provides a block diagram of a chemical analyzer packageaccording to some embodiments of the invention where the packageincludes an output device while a power supply and/or analyzer may beseparate from the package.

FIG. 10C provides a block diagram illustrating some preferential sizes,weights, and power consumption levels associated with a compact chemicalanalyzer package according to some embodiments of the invention.

FIG. 11A provides a schematic illustration of a chemical analysis systemaccording to some embodiments of the first class of embodiments.

FIG. 11B provides a schematic illustration of a chemical analysis systemaccording to some embodiments according to the second class ofembodiments.

FIG. 12 provides a schematic depiction of an analytic instrumentaccording to some additional embodiments of the invention.

FIG. 13 provides a schematic depiction of an analytic instrumentaccording to some further embodiments of the invention.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS OF THE INVENTION

Deep UV Radiation Production Methods and Sources

To avoid the difficulties, set forth above, related to producing deep UVsemiconductor sources, Applicants have developed a pumping approach thatuses ballistic electron beam injection directly into the active regionof a wide band gap semiconductor material. One element thatdistinguishes some embodiments of the invention from the teachings aboutelectron beam pumping noted above is that none of the publicationsdiscuss, describe, or suggest the use of wide bandgap semiconductormaterials (i.e. semiconductor materials having a band gap greater than3.5 eV, corresponding to wavelengths less than 400 nm, more preferablygreater than 4.15 eV, corresponding to wavelengths less than 300 nm, andmost preferably greater than 4.97 eV, corresponding to wavelengths lessthan 250 nm). Furthermore these references fail to teach the use ofGroup III nitride semiconductor material systems, such as an AlGaNalloy, for producing laser output using ballistic electron beam pumping.These references also fail to teach the use of diamond for producinglaser output using ballistic electron beam pumping. Another element thatdistinguishes some embodiments of the invention from these priorteachings is that they do not discuss, describe, or suggest producinglasers emitting below 300 nm, e.g. in the 200 nm to 300 nm range, usingthese wide bandgap semiconductor materials via ballistic electron beampumping.

In contrast to a pn-junction laser device, where low energy electrons(e.g. electrons having an energy less than 5 to 10 eV) are used witheach producing approximately one electron-hole pair, the ballisticelectron injection approach uses high energy electrons (e.g. electronshaving an energy on the order of 5 KeV to 10 KeV) are used with eachelectron entering the semiconductor material to successively lose itsenergy in multiple energy exchange collisions producing hundreds ofelectron-hole pairs. As a result, these electron-beam-pumpedsemiconductor ultra-violet optical source (ESUVOS) devices require aboutthe same pumping power density as a pn-junction device, but at hundredsof times less current density and hundreds of times higher voltage.Employing the ESUVOS concept, miniature semiconductor incoherent andlaser sources can be produced which emit in the wavelength range fromabout 200 nm to 365 nm simply by altering the alloy composition of theAlGaN material. In still other employments of the ESUVOS conceptsources, e.g. laser or incoherent sources, emitting at about 227 nm maybe produced using natural or synthetic diamond as the emission medium.

The emission wavelength from aluminum-gallium-nitride (AlGaN) may bevaried based on the aluminum mole fraction within the alloy, as shown inFIG. 1. Pure aluminum-nitride has a bandgap of 6.2 eV, corresponding toa 200 nm wavelength. Pure gallium-nitride has a bandgap of 3.6 eV,corresponding to a 360 nm wavelength. Intermediate bandgaps may beachieved by adding varying amounts (x) of aluminum in Al_(x)Ga_(1−x)N.From FIG. 1 it can be seen that aluminum mole fractions greater thanabout 60% can achieve emission wavelengths below 250 nm.

As noted above, problems have presented themselves when trying toproduce AlGaN semiconductor lasers having aluminum mole fractionsgreater than about 30%. The two primary problems include: (1) theinability to p-dope AlGaN alloys with the required Al content and (2)the inability to form ohmic contacts to AlGaN materials with high Alcontent. According to some embodiments of the invention, the problemswith p-doping and ohmic contacts are addressed by directly pumping thebandgap using ballistic electrons from an electron gun (e.g. a fieldemission source). In some of these embodiments, the semiconductormaterial (e.g. AlGaN) and the electron source are contained in a highlyevacuated or vacuum vessel (e.g. a miniature vessel). In otherembodiments, one or both of the electron source and the semiconductormaterial may form portions of a hermetic envelope which allows a desiredenvironment, e.g. an evacuated region, in which electrons may pass fromthe cathode to the semiconductor material. The vessel may also contain asource of acceleration voltage or one or more electrical feedthroughsthat connect to such a source. The vessel may also contain a focusingand/or extraction grid (e.g. to focus electrons along a length of a gainmedium that is to be excited).

The configurations of ESUVOS devices can take many forms and may beclassed as incoherent light emitting devices or coherent light emittingdevices (i.e. laser devices). In either class of device thesemiconductor medium may include, for example, an aluminum galliumnitride alloy or range of alloys which are in the form of one or moreepitaxially grown films located on a substrate material usually with avariety of buffer and cladding layers between the substrate and theoptically active region of the film or films. The substrate materialmay, for example, be sapphire or silicon carbide, aluminum nitride,gallium nitride or other suitable materials compatible with the AlGaNepitaxial film or films. The optically active region of the film orfilms is preferably located at or close to the surface of the depositedmaterials, opposite the substrate, in order to minimize the scatteringof ballistic electrons prior to generation of electron-hole pairs in theactive region.

In the case of the incoherent light emitters, some of the devices may betermed electron-beam-pumped light emitting triode (ELET) devices as theytypically have three electrodes (e.g. a cathode, an anode, and anextraction control grid). Other devices may have additional electrodes.As used herein triode shall generically be used to refer to radiationemitting devices that have an anode and a cathode and at least oneintermediate electrode. In other words, unless further limited by thecontext, a triode device shall contain at least three electrodes but maycontain more than three electrodes. In some embodiments of the inventiona radiation emitting device may use only two electrodes (i.e. an anodeand a cathode). If an extraction control grid is used, it may allowcontrol of the electron current flowing between the cathode and anode.In ELET devices radiation emission is dominantly out the back surface ofthe substrate and may be enhanced by addition of a thin photonreflective film (e.g., 30 nm to 50 nm of aluminum on the surface ofpreviously deposited films). In other words, the reflective film may beformed between the cathode and the semiconductor material and is madethin enough to allow electrons to pass through it to the semiconductormaterial while still providing optical reflectivity. This film (e.g.aluminum film) may serve as an anode as well as a mirror. As a mirror itmay reflect the cathodoluminescent emission (produced from the activeregion of the semiconductor) in the original propagation direction ofthe electron beam, thereby increasing the radiance and power of the ELETsource in that direction. The shape of the optical emission area isdetermined by the shape of the electron beam pumping current. In someembodiments, the electron beam may take on a circular geometry, whichwill produce a circular Lambertian emission profile, plus some edgeemission from the ELET die. In other embodiments, the beam may take onan elongated configuration or some other configuration.

Such ELET devices may be constructed in different ways. For example,they may be constructed from processes similar to those used in themanufacture of semiconductor devices where individual functional andstructural components are formed in situ in their desiredconfigurations. In such processes it may be possible to form multipledevices, in whole or in part, on a single substrate or wafer after whichdicing may occur to separate the individual devices (i.e. formation mayoccur in a batch process whereby multiple devices may be producedsimultaneously on the same wafer or substrate). In other embodiments, amore traditional process may be used wherein some individual componentsof the devices may be formed separately and then placed in desiredrelative positions via an assembly process (e.g. the substrate, activesemiconductor film, and anode may be produced in one process while thecathode and any control grids may be formed in one or more separateprocesses and then aligned and mounted in desired positions relative tothe active semiconductor medium).

An example of an ELET device is illustrated with the aid of the cut viewshown in FIG. 2. The device 1 of FIG. 2 includes a sapphire substrate 2,on which an aluminum nitride (AlN) buffer layer 4 is formed. In turn agraded cladding layer 6, e.g. of aluminum gallium nitride AlGaN, isformed. Immediately above the AlN layer, the gallium content of thecladding layer is low (e.g. starting at 0% to 30%) and increases to aconcentration equal to or approaching that which an overlying activelayer 8 of semiconductor material will have. The graded cladding layermay be formed from a plurality of separated applied layers havingincreasing Ga content.

The active semiconductor layer 8 is formed from one or more films ofAl_(x)Ga_(1−x)N having mole fractional content “x” of Al and “1−x” of Gawhich are intended to produce a desired wavelength or wavelength band ofradiation.

The active layer is in turn overlaid by a graded cladding layer 12formed of AlGaN which progressively decreasing gallium content. Thegraded cladding layer 12 is in turn overlaid by an anode contact layer(e.g. formed of aluminum which has a thickness appropriate to allow highenergy electrons to pass through it and providing an opticallyreflective surface for photons generated in the active layer 8. Asshown, the anode may have an exposed area (e.g. the upper left portion)which may be used to make electrical contact with a power supply via awire bond or other conductive lead.

Overlaying the anode 14 is a patterned dielectric material 16. Thisdielectric helps define the electron acceleration gap between the anodeand the cathode. It may be formed of any appropriate material and tohave cross-sectional and height dimensions that allow appropriateexcitation of semiconductor material to occur.

Overlaying the dielectric 16 is a focusing grid structure 18. It mayinclude an exposed region for making electrical contact (e.g. the leftmost region of the layer). The focusing grid electrode 18 may beoverlaid, in turn, by a patterned dielectric 22 which in turn may beoverlaid by a patterned extraction gird layer 24. It may include anexposed region for making electrical contact (e.g. the left most regionof the layer). The extraction grid layer may in turn be overlaid by apatterned dielectric 26 which in turn may support a cathode 28 (i.e. anelectron source) which in turn may have an electrical contact 30 locatedon its upper surface. In some embodiments, the cathode may include adoped silicon substrate on which an array of carbon nanotubes arelocated. The Array may take any desired shaped which will result in anappropriate electron bombardment pattern onto the active material afterthe beam is focused by any focusing gird.

The layers 16-28 are patterned to form a void or gap 28 through whichelectrons can travel from the cathode to the anode when appropriateelectrical power (i.e. current and voltage are applied to the cathode,anode, extraction grid and focusing grid. The gap may be surrounded byhermetic structures (not shown) which will allow a controlledenvironment to exist along the path taken by the shaped electron beamthat is created. During operation radiation is produced within theactive layer 8 and is emitted from the lower portion of the substrate,e.g. along path 38.

In some alternatives of this first example embodiment, the active layermay be deposited in a blanket fashion such that it exists over theentire prior deposit while in other alternatives it may be patterneddeposited so that it exists in a region or regions that approximate thearea or areas intended for excitation. Similar alternatives exist forthe graded cladding layers and even the buffer layer. Similarly theanode layer may take the form a blanket or of a patterned deposit sothat the anode exists in the regions to be excited, in a contact regionand along a bridging path. In the case of patterned depositions regionsnot forming part of the active structure may be filled in with othermaterials. To minimize processing complexities and the risks of crystalstructure mismatches and the like, the blanket formation alternativesare preferred.

In still other alternative embodiments, the AlGaN alloy and associatedsubstrate, cladding layers, and buffer layers may be replaced byepitaxial deposited carbon (e.g. a diamond or diamond-like material) andappropriate substrate, cladding layers, and buffer layers. In stillother alternative embodiments, the AlGaN alloy and associated substrate,cladding layers, and buffer layers may be replaced by a piece of anatural or synthetic diamond or diamond-like material that isappropriately shaped and which may or may not be attached to asubstrate. Appropriate mirrors may be formed on one or more surfaces ofthe diamond, e.g. cleaved surfaces) or they may be located at a distancefrom diamond and held in place by appropriate mounting elements. Thediamond or diamond-like material is preferably of high purity but it ispossible that in some embodiments impurities may be included (vianatural formation, doping, diffusion, or the like) and may result inminor or significant variations in diamond's nominal bandgap emissionwavelength of approximately 227 nm.

In some alternative embodiments, the focus grid and/or the extractiongrid may be removed. The various layers may each be formed as a singlelayer or as a plurality of layers. The anode contact may be located in adifferent location (e.g. below the upper cladding layer). The anodecontact may not function as an effective mirror. The upper claddinglayer may be removed or it may have a different height and/orconcentration gradient and/or initial or final concentration levels thatdifferent from those used in the lower cladding layer. The beam may bemade to leave a different surface of the structure. A second AlN bufferlayer may be provided above the upper cladding layer 12 (e.g. below theanode layer 14).

In some embodiments, the ELET may be formed in part or entirely usingsemiconductor or MEMS (microelectromechanical system) fabricationtechniques, while in other embodiments, it may be formed from acombination of semiconductor or MEMS fabrication techniques incombination with discrete component assembly operations, hermeticsealing and evacuating operations, and the like.

In various embodiments, the physical dimensions of various componentsmay take on different values. In some embodiments, for example, thesubstrate may have a thickness in the range of 0.1 mm to 0.5 mm and havecross-sectional dimensions in the range of 0.2 mm to 1.0 mm In someembodiments the AlN layer above the substrate may have a thickness inthe range of 100 nm to 2000 nm, the adjacent graded cladding layer mayhave thickness in the range of 10 nm to 100 nm, the active semiconductorregions may include multiple quantum wells (e.g. 10 to 50) with eachincluding a layer of Al_(x)Ga_(1−x)N (e.g. having a thickness in therange of 0.1 nm to 1 nm separated by a layer of AlN (e.g. having athickness in the range of 0.1 nm to 1 nm the graded cladding layer abovethe active semiconductor layer may have a thickness in the range of 10nm to 70 nm, while an overlying AlN layer may have a thickness in therange of 100 nm to 500 nm, and an overlying anode or mirror layer may athickness in the range of 10 nm to 100 nm. In some embodiments, the gap32 may be in the range of 100-500 μm in height. In other embodiments,other dimensions may be used.

In some alternative embodiments one or more of the dielectrics 16, 24,and 28 that are located between the anode 14 and focusing grid 18, thefocusing grid 18 and the extraction grid 24, and the extraction grid 24and the cathode 28, respectively, may be replaced with othernon-conductive structures and structural configurations that hold theelectrodes in their desired relative positions (e.g. dielectric portionsof a hermetic envelope in which the light source is located).

Laser versions of an electron-beam-pumped semiconductor ultra-violetoptical source (ESUVOS) may take different forms. For example, they maytake the form of (1) an edge emitter (i.e. radiation is emitted from aside or edge of the semiconductor film) or (2) a vertical cavity surfaceemitter (e.g. radiation is emitted the back surface of a semiconductorfilm into the substrate and then from the back surface of thesubstrate). In both forms, the device may take the form of anelectron-beam-pumped laser triode, or ELT, similar to the ELET discussedabove while in other forms more than three or less than three electrodesmay be used. In either form, an electron beam may pump an opticallyactive region near the surface of an epitaxial deposited layer of asemiconductor material such as, for example, an AlGaN alloy, diamond ordiamond-like carbon, or it may pump a surface of a piece of natural orsynthetically produced diamond or diamond-like carbon of desired shape.

In the case of the electron-beam-pumped vertical cavity surface emittinglaser (EVCSEL) device, the electron beam pumps the semiconductor regionin a fashion similar to that described above for ELET device except thatmirror coatings are applied on both sides of the epitaxial film or pieceof emission material or on surfaces parallel to the surfaces of theepitaxial semiconductor film or surfaces of the piece of emissionmaterial to form an optical resonant cavity for use at a desired designwavelength of the device (in some embodiments, thermal control may beused to obtain desired cavity length). In one simple case, the top andbottom of the AlGaN die are coated with a thin aluminum mirror coating(e.g. having a thickness of about 30 nm to 50 nm each) to form theresonant cavity. The thickness of the coating on the entry surface islimited on the one hand by a need to get the electrons into the activeregion and on the other by the need to form a mirror of desiredreflectivity. The thickness of the coating on the back side (i.e.substrate side) of the active region is restricted only by the need toform a mirror of desired reflectivity. Alternatively, the mirrorcoatings may be applied on either side of the semiconductor material.For an EVCSEL, the electron beam current density needs to be higher thanin the case of the ELET to enable the device gain to exceed devicelosses. In an EVCSEL the electron pumping beam may take on any desiredcross-sectional shape, e.g. a circular shape. An example of an EVCSELdevice is illustrated with the aid of FIG. 3.

The laser device 41 in the example of FIG. 3 is similar to the ELETdevice of FIG. 2 and, as such, similar elements are marked with similarreference numerals. The primary difference between the laser 41 of FIG.3 and the incoherent source 1 of FIG. 2 is that the laser includes anadditional mirror coating 40 that is applied to the substrate side ofthe active medium. As illustrated, in different embodiments, the mirrorcoating may be placed in different locations as indicated by references40A, 40B, 40C, or 40D. The mirror coating will be located at one of thealternative locations 40A-40D as shown in the figure. In otheralternative embodiments, the mirror may be located in still otherpositions, for example, it may be displaced from the lower surface ofthe substrate and held in position via appropriate alignment structuresor standoffs. In embodiments where a piece of semiconductor, e.g.diamond, is used as the lasing medium, the cladding layers, bufferlayers, and even substrate may be removed and the mirrors formed on ormounted to the surfaces of the semiconductor or they may be held byappropriate fixturing in a desired position relative to both thesemiconductor material and the beam of excitation electrons used. Instill other embodiments, additional optical components may be added,such as Brewster windows, direction reorienting mirrors, prisms or thelike. The mirror may or may not be located within an evacuated chambercreated to allow free electrons to travel to the anode/semiconductormaterial with minimal energy losses. The mirror positioning shown withreference 40A is preferred for many embodiments as the mirror coatingmaterial (e.g. aluminum, will not interface with any desired crystalmatching between the material junctions in the epitaxially depositedfilms.

In the case of an edge emitting electron-beam-pumped laser (EEEL)device, the electron beam typically takes a planar form so that itessentially forms a line of incident electrons on the semiconductormaterial which is to be activated. The line may be formed from a singleelongated emission zone or a plurality of discrete but closely spacedemission regions. The long dimension of the incident beam extends alongan axis of the active semiconductor medium. The activated medium emitsradiation in all directions (including out of the upper and lowersurfaces of the gain medium and out of the edges of the medium). A pairof mirrors are used to define an optical gain path that extends throughand to opposite edges of the activated medium. In some embodiments, themirrors may be located on and bonded to cleaved facets of thesemiconductor medium while in other embodiments, the mirrors may bespaced from the semiconductor material. In this case, the ballisticelectron beam produces a gain region along the optical axis defined bythe mirrors.

A first example of an EEEL device is shown in the perspective view ofFIG. 4A. Portions of the device that are similar to those in FIGS. 2 and3 are indicated with like reference numerals.

In this embodiment the laser 51 includes a sapphire substrate 2 whichmay have a width dimension, W, in the range of 250-750 μm (e.g. 500 μm)and a depth dimension, D, in the range of 350-1050 μm (e.g. 700 μm). Theoverall height, H, of the laser may, for example, be in the range of300-1200 microns (e.g. 500 μm). The laser produces a beam 58 from anedge of the excited AlGaN semiconductor material 8. Mirrors orreflective surfaces (not shown) are located on the front and back facesof the semiconductor. These mirrors form a resonant cavity. These mirrorsurfaces may be limited to height and/or width regions corresponding tothe region of the semiconductor material that is to be excited and fromwhich desired radiation is to be emitted. In other embodiments, theentire front and back surfaces of the substrate, semiconductor, andadditional layers may be coated. In still other alternative embodiments,the mirror coatings may be displaced from the semiconductor material andheld in place by appropriate surfaces and spacers or alignment fixtures.The mirrors may be formed within a hermetic envelope, form part of ahermetic envelope, or be located outside a hermetic envelope. In somealternative embodiments, additional optical elements may be locatedbetween the semiconductor material and the mirrors.

The semiconductor material, e.g. AlGaN of having appropriate fractionalmole concentration of Al, may be formed on various layers of othermaterials (not shown) which are deposited on the substrate material andit may also be overcoated with additional layers of various materials.For example, buffer layers, cladding layers, and/or an anode materialthrough which electrons can pass to excite the semiconductor materialand to which electrons can be drawn after excitation.

As shown, an electric contact 14′ for the anode may be formed on aportion of the semiconductor material or on one of the overlying layers.Preferably the portion of the semiconductor material 8′, located betweenthe cavity mirrors, is excited so as to maximize the gain of the system.The X&Y dimensions of the semiconductor material excited by an electronbeam traveling in the Z direction may be controlled by controllingeither the X & Y dimension of the semiconductor material and/or bycontrolling the X & Y dimensions of the bombarding electron beam. Theabsorption of the electrons along the Z-dimension may be tailored tooccur within the semiconductor material by selecting the bombardmentvoltage (e.g. to maximize laser output) and/or by selecting thethickness of the semiconductor material and/or the thicknesses of andmaterials chosen to overlay the semiconductor material.

Above material 8, a gap 32 exists in which a vacuum is preferablycreated. This vacuum may be limited to this gap region, it may surroundall or a portion of the semiconductor material and/or its substrate,and/or the cathode (to be discussed herein after). In the variousembodiments, the vacuum region may be defined by a hermetic envelope.The hermetic envelope may surround all or a portion laser componentsshown in FIG. 4A. In some embodiments, a portion of the laser componentsshown in FIG. 4A may form parts of the hermetic envelope. In someembodiments, a getter material may be located within the hermeticenvelope to help maintain the integrity of the vacuum. In someembodiments the gap 32 may be, for example 100-500 μm in height. In thisgap, electrons are accelerated toward the anode to cause hole/electroncreation in the active semiconductor material. Above the gap a cathode28, such as a linear carbon nanotube (CNT) array, is located which issupported by a cathode substrate 60, for example a doped siliconsubstrate). The CNT array 28 has a length that corresponds to the lengthof an excitation path in the active semiconductor material 8 along whichlaser radiation will be produced. In some alternative embodiments,instead of using a linear array of carbon nanotubes, a diamond microtipfield emission array may be used, or even a thermionic emission cathodemay be used.

In gap 32, between and separated from the CNT Array and the anode, anoptional extraction grid 24 is shown s which includes an elongatedopening or array of openings (each, for example, having a 2 μm diameter)through which electrons can pass. The cathode and extraction grid areconfigured to give rise to a slit shaped electron beam which impinges onthe active semiconductor material 8 to produce an excited medium whichcan give rise to laser radiation from the edge of the semiconductordevice. The device also includes cathode contact 30, and a grid contact24′ and appropriate distances between the anode, the cathode, and theextraction grid may be set and maintained by dielectric materials 16 and22.

Upon application of appropriate voltages and current, a laser beam 58may be generated. This laser beam 58 may, for example, be used toirradiate a sample or surface of a sample to be analyzed. In someembodiments, for example, the field emission elements may be set at zerovolts, the extraction grid may set at minus 10 volts while the anode maybe set at plus 5000 volts. In other embodiments an electron lensstructure may be provided between the extraction grid and the anode tohelp focus the electron beam onto the active semiconductor target (e.g.AlGaN target).

FIGS. 4B and 4C provide cut views of an example EEEL device. Likeelements of FIGS. 4B and 4C are depicts with similar reference numeralsto those used in FIGS. 2-4A. The device is similar but not identical tothat of FIG. 4A. FIG. 4B depicts a cut view in the X-Z plane while FIG.4C depicts a cut view in the Y-Z plane. In FIG. 4C the laser beam 58 canbe seen projecting from the left side of the device while FIG. 4B showsthe laser beam having a circular cross-section and being projected outof the plane of the figure. FIG. 4B depicts dielectric standoffs 16, 22,and 26 which cannot be seen in FIG. 4C. FIG. 4C depicts the electronbeam has having a length EL while FIG. 4B depicts the electron beam ashaving a width EW. FIGS. 4B and 4C depict several deposited layers whichare located on substrate 2. These layers include (1) a buffer layer 4,e.g. formed of AlN, (2) a graded cladding layer 6, e.g. formed of AlGaNand having an increasing Ga content with height, (3) the activesemiconductor layer or layers 8, e.g. formed of AlGaN having a molefraction of Al selected to produce radiation of a desired outputwavelength, (4) a graded cladding layer 12, e.g. formed of AlGaN with anAl concentration that decreases with height, and (5) an anode layer 14,e.g. formed of aluminum through which excitation electrons may pass. Insome alternative elements a buffer layer may be including betweencladding layer 12 and anode layer 14. In still other embodiments, fewerdeposited layers may exist while in other more deposited layers mayexist. In still other embodiments, the types of materials deposited maybe different or a substrate of different material may be used. In FIG.4C, cavity mirrors 60A and 60B may be seen. In some embodiments, mirror60A may be highly reflective while mirror 60B may be partiallyreflective (e.g. with reflectivity chosen to yield desired gain anddesired output. In other embodiments, other reflectivity configurationsmay be used, e.g. both mirrors may be partially reflective so that abeam is emitted from both ends of the device.

In various embodiments of the invention, whether devices are of the ELETtype, the EVCSEL type, or of the EEEL type, the various layers ofdeposited materials may have various thicknesses. For example, an AlNlayer above the substrate may have a thickness in some embodiments inthe range of 100 nm to 1500 nm (e.g. about 1000 nm), an adjacent gradedcladding layer may have thickness in the range of 10 nm to 100 nm (e.g.about 70 nm), an active semiconductor regions may include multiplequantum wells (e.g. between 20-100, e.g., about 50) with each includinga layer of Al_(x)Ga_(1−x)N (e.g. having a thickness in the range of 0.1nm to 1.5 nm, e.g. 1 nm) separated by a layer of AlN (e.g. having athickness in the range of 0.1 nm to 1.0 nm, e.g. 0.3 nm), a gradedcladding layer above the active semiconductor layer may have a thicknessin the range of 10 nm to 100 nm, (e.g. about 70 nm), while an overlyingAlN layer may have a thickness in the range of 100 nm to 1000 nm, e.g.about 500 nm.

As noted in the above examples, it is typical for ESUVOS devices of thepresent invention to make use of an extraction grid or gate sealed in ahermetic volume through which the electrons flow and which may extendbeyond or be bounded by the cathode on one end and the surface of thesemiconductor gain medium on the other. However, it should be understoodthat other configurations are possible. ESUVOS devices may not involveuse of an extraction grid or gate but use other means to control theelectron beam current. Such other means may include current limitedpower supplies, feedback loops keyed off radiation production ordetected current flow, or the like.

Sources of electrons can be, for example, simple thermionic sources ormore advanced field emission devices such as, for example, carbonnanostructures (e.g. nanotubes), diamond microtip arrays, or similarnaturally negative electron affinity devices with electric fieldenhancement in the form of, for example, very sharp pointed electronemitter arrays. These electron sources have demonstrated the ability toemit the required, approximately 10 to 100 A/cm², current densitiesneeded to adequately pump AlGaN laser devices. The required pumpingcurrent density is several orders of magnitude lower than that typicallyused in pn-junction laser devices. However, the electron energy is alsoseveral orders of magnitude higher, so that the pumping power densityremains about the same.

Photon emission media other than AlGaN (i.e. gain medium in the case ofa lasing device) may be used. For example, pure or substantially purediamond, of the natural or synthetic type, may be pumped by a highenergy electron beam such that band gap photon emission at about 227 nmis excited. The diamond may be epitaxially deposited on buffer andcladding layers on a substrate or instead may take the form of anappropriated shaped piece of naturally occurring or syntheticallyproduced diamond or diamond-like carbon. The medium may be appropriatelyshaped, e.g. cleaved or sliced, from a natural source or it may becleaved or sliced from a boule of synthetically produced diamond. Thediamond piece may take on a variety of shapes. For example, it may besubstantially pill shaped in the case of an ELET or EVCSEL device or itmay be elongated, or rod-like, in the case of an EEEL device.

FIGS. 5A-5F provide schematic depictions of various states in an exampleprocess of forming the grid and cathode portion of a semiconductor laseraccording to some embodiments of the invention. FIG. 5A depicts asilicon wafer 72 having a thickness of, for example, about 300 μm, andwhose lower surface has received a layer of silicon oxide, SiO, 74. FIG.5B depicts the state of the process after the top side of the siliconwafer has received a coating of thick photoresist (PR)) 76. FIG. 5Cdepicts the state of the process after the photoresist 76 has beenpatterned and the silicon wafer 72 etched through (e.g. using DRIEetching) to form dicing lanes 80 and large gird aperture 82 and leavingintact the layer of silicon oxide 74. FIG. 5D depicts the state of theprocess after (1) the structure of FIG. 5C is inverted, (2) thephotoresist 76 has been removed, (3) a combined coating 84 of chromium(Cr) followed by gold (Au) has been applied (e.g. by sputtering), (4) acoating of photoresist 186 has been applied to the gold and patterned toform openings 90 corresponding to locations where gridopenings/apertures (elongated array of openings) will be located andopenings 88 corresponding to dicing lines, and (5) the chromium and goldlayers have been etched away in the areas 190 and 188 via the openingsin the photoresist. FIG. 5E depicts the state of the process after thephotoresist is further patterned and developed to create grid contactsand leaving photoresist on top of grid. FIG. 5F depicts the state of theprocess after (1) the SiO 74 is dissolved in the region of opening 82 tocreate a chip with a suspended grid, (2) a cathode support 92 andcathode 94 (e.g. including a carbon nanotube array) is bonded (e.g.glued) to photoresist to yield a cathode located above the openings inthe grid array.

Other steps or operations (not shown) may be performed. For example gridwires may be added. The grid and cathode portion may be bonded, directlyor indirectly to a piece of semiconductor photon emission material (e.g.diamond or diamond-like carbon) that may or may not be attached to asubstrate. The grid and cathode portion may be bonded to an emissionmedium formed from deposited layers (e.g. including a buffer layer,graded cladding layers, an active semiconductor material, and an anodematerial) on a substrate (e.g. a sapphire substrate). In otherembodiments, the grid and cathode portion may not be bonded to thesemiconductor material but each may be mounted in relative positions viaappropriate fixed or adjustable mounts. In some embodiments, theformation of the cathode, gird and support structure may be formed on adevice-by-device basis while in other embodiments, batch formation maybe used. Similarly, device-by-device formation may be employed inattaching the sapphire substrate and active semiconductor material tothe cathode/grid assembly or batch processing and then dicing may beused. Similarly mirror coating may be applied on a device by devicebasis or via batch processing.

In some alternative embodiments the grid and cathode portion of a deviceformed according to the process of FIGS. 5A-5F may be implemented on aworking substrate comprising a piece of the semiconductor emissionmaterial, with or without a primary substrate, or on the epitaxiallygrown layers of material located on a primary substrate.

Various alternative formation processes may be used, various otheralternative design configurations are also possible, and/or variouschanges may be made to the materials used in the formation of variousportions of the radiation source (i.e. laser or incoherent source).These variations and changes will be apparent to those of skill in theart upon review of the teachings herein.

Analytical Methods and Instruments

Various embodiments of the invention provide novel analytical methodsand/or instruments for providing at least partial chemical analysis ofsamples. FIG. 6A provides a simplified block diagram of components of achemical analysis system or apparatus according to a first class ofanalytical methods and instrument embodiments of the invention. Thesystem 100 includes a semiconductor laser 102 (e.g. a laser of selectedfrom one of the types discussed above) which produces radiation 104which is used to illuminate a sample 106 (which is typically not part ofthe apparatus). In preferred embodiments of the invention, the radiation104 impinging on the sample is in the ultraviolet (i.e. UV) range. Theapparatus may include a window through which the sample may beirradiated and through which resulting radiation may be received; acavity in which the sample may be placed, the sample irradiated, andresulting radiation produced; a transparent tube in which a quantity ofthe sample may be flowed, irradiated, and resulting radiation detected;or the like (not shown). Different types (or bands) and wavelengths ofradiation 108 may come from sample 106 as a result of irradiation by thesemiconductor laser. Depending on the excitation radiation 104, thewavelengths 108 coming from sample 106 may be, for example, of theRayleigh type, Raman type, fluorescence type, or phosphorescence type.The resulting radiation 108 may be in the ultraviolet range (i.e. UV),visible range, or even IR range.

The radiation 108 coming from sample 106 is made to impinge directly(i.e. without intermediate optics, e.g. mirrors, lens, filters,diffraction gratings, or the like) or indirectly (i.e. via at least oneoptical component) on at least one spectral filter 112 which in turnpasses (e.g. transmits or reflects) selected radiation 114, if presentin incident radiation 108, onto one or more radiation detectors 116. Theradiation detector may then produce a signal 118 (e.g. an electricalsignal) that is sent to an analyzer 122 (e.g. a programmable electronicdevice) that compares information coming from the detector(s), alongwith information corresponding to the wavelengths passed by filter 112,to data stored about one or more known elements, molecules, or the like.The analyzer produces a result which may be indicative of a recognizedrelevant substance, indicative of a recognized but irrelevant substance,indicative of an inconclusive or unrecognized substance, indicative of aneed to perform additional analysis, and/or indicative of a relativeconcentration or quantity of the substance present, or the like).

In some variations of the first class of embodiments set forth in theblock diagram of FIG. 6A the semiconductor laser may be of the EEEL typewhile in other variations it may be of the EVCSEL type. In otheralternative embodiments, the semiconductor laser may be replaced by anincoherent source such as an LED or ELET (e.g. embodiments wherefluorescence and/or phosphorescence detection will be performed).

In some alternative embodiments the analyzer may be replaced by anoutput device that transmits information about the detected radiation toa separate device which performs the analysis function.

In some other alternative embodiments, the system may also include areceiver (e.g. a hardwired, IR, or microwave communication link) forobtaining instructions and or comparison data from an external device.

In some alternative embodiments the device may include a control panelfor receiving input from an operator. It may also include one or more ofa visual display, an audio signaling subsystem, and/or a tactile (e.g.vibrational) subsystem for communicating selected information to anoperator or to persons located in the vicinity of the device. In somealternative embodiments, the system may include output signal capabilitythat can be used to control external devices such as fans, doors,sprinklers, and the like. These functionalities may be provided forexample via one or more appropriately programmed microprocessors,appropriately configured state machines, associated temporary andpermanent memory, and associated input and output subsystems which arewithin the skill of the art.

According to some embodiments of the invention, preferred deepultraviolet light sources, and most particularly laser sources, aresmall (e.g. under a volume of 4 liters, more preferably under a volumeof 2 liters, even more preferably under a volume of 0.5 liters, and mostpreferably under a volume of 0.125 liters), light weight (e.g. lightenough to be held in the hand, more preferably weighing less than 20pounds, even more preferably weighing less than 5 pounds, and mostpreferably weighing less than 2 pounds), and consume only small amountsof power (e.g. consuming under 100 watts average power during operation,more preferably under 10 watts, even more preferably under 2 watts, andmost preferably capable of being powered from one or more batteries).Such ultraviolet sources may enable many analytical instrumentapplications which may benefit from the use of induced nativefluorescence or Raman spectroscopy to detect and identify unknownchemical substances. Semiconductor lasers, of the type discussed above,can enable such applications. According to some embodiments of theinvention, such semiconductor lasers can be fabricated which emit in theultraviolet range (i.e. wavelengths below 400 nm), and preferably atwavelengths below about 300 nm, and even more preferably at wavelengthsbelow about 250 nm.

Some embodiments of the invention provide analytical methods and/orinstruments for providing at least partial chemical analysis of samples.FIG. 11A provides a simplified schematic diagram of components of achemical analysis apparatus or system according to a first class ofanalytical instrument embodiments of the invention. The system 300includes a semiconductor laser 302 that produces ultraviolet (UV)radiation 304 (e.g. radiation having a wavelength less than about 300nm) that is used to bombard or expose a sample 306 (this sample is nottypically considered part of the apparatus or device). Preferredwavelengths of radiation are below 300 nm, more preferably below 280 nm,even more preferably below 250 nm but in other embodiments it may bepossible to use longer wavelengths of radiation or even shorterwavelengths of radiation.

The apparatus may include (1) a window, e.g. formed of quartz or otherUV transmitting material, through which the sample may be irradiated andthrough which resulting radiation may be received; (2) a cavity in whichthe sample may be placed, the sample irradiated, and resulting radiationproduced; (3) a transparent tube in which a quantity of the sample maybe flowed, irradiated, and resulting radiation detected; or the like(not shown). Different types (or bands) and wavelengths of radiation 308may come from sample 306 as a result of irradiation by the semiconductorlaser 302. Depending on the excitation radiation 304, the wavelengths308 coming from sample 306 may be, for example, of the Rayleigh type,Raman type, fluorescence, or phosphorescence type. In still otherembodiments where higher energy incident photons 304 are used, Rayleighscattering may be detected and used to analyze properties in a very thinlayer at the surface of a sample. The resulting radiation 308 may be inthe ultraviolet range (i.e. UV), visible range, or even IR range.

The radiation 308 coming from sample 306 is made to impinge directly(i.e. without intermediate optics, e.g. mirrors, lens, filters,diffraction gratings, or the like) or indirectly (i.e. via at least oneoptical component) 307 on at least one spectral filter 312 which in turnpasses (e.g. transmits or reflects) selected radiation 314, if presentin the incident radiation 308, onto one or more radiation detectors 316.The radiation detector may then produce a signal 318 (e.g. an electricalsignal) that is sent to an analyzer, e.g. a programmable electronicdevice, (not shown) that compares information coming from thedetector(s), along with information corresponding to the wavelengthspassed by filter 312, to data stored about one or more known elements,molecules, or the like. The analyzer produces a result which may beindicative of a recognized relevant substance, indicative of arecognized but irrelevant substance, indicative of an inconclusive orunrecognized substance, indicative of a need to perform additionalanalysis, and/or indicative of a relative concentration or quantity ofthe substance present, or the like. In various alternative embodiments,the analyzer may perform additional functions or simply performdifferent functions depending on the needs dictated or desired invarious potential circumstances. The analyzer may be a single device ormultiple devices.

In other embodiments, instead of producing photons that undergofiltering and then detection, an optical beam induced current, surfaceelectrovoltage spectroscopy, or the like may be used to provideanalytical characterization of a sample.

In some variations of the first class of chemical analysis embodimentsset forth in the block diagram of FIG. 6A the semiconductor laser may beor may include an electron beam pumped semiconductor laser.

In some alternative embodiments the analyzer may be replaced by anoutput device that transmits information about the detected radiation toa separate device which performs the analysis function.

In some other alternative embodiments, the system may also include areceiver (e.g. a hardwired, IR, or microwave communication link) forobtaining instructions and or comparison data from an external device.

In some alternative embodiments the device may include a control panelfor receiving input from an operator. It may also include one or more of(1) a visual display, (2) an audio signaling subsystem, and/or (3) atactile (e.g. vibrational) subsystem for communicating selectedinformation to an operator or to persons located in the vicinity of thedevice. In some alternative embodiments, the system may include outputsignal capability that can be used to control external devices such asfans, doors, sprinklers, or the like. These functionalities may beprovided for example via one or more appropriately programmedmicroprocessors, appropriately configured state machines, associatedtemporary and permanent memory, and associated input and outputsubsystems which are within the skill of the art.

FIG. 6B provides a block diagram illustrating examples of various typesof analysis that may be performed by various embodiments of the firstclass of embodiments. The type of analysis performed is determined bythe relationship between the radiation incident on a sample and the typeof radiation coming from the sample and as such for a given incidentwavelength, the type of analysis performed is related to the spectralfilters chosen. As indicated, the chosen spectral filters 112 mayresult, for example, in a Raman analysis 204, a fluorescence analysis206, a phosphorescence analysis 207, a combined or two-step or eventhree step analysis 208-211. Two step analyses may include fluorescenceand Raman 208, phosphorescence and Raman 209, or fluorescence andphosphorescence 210. In some two-step embodiments the measurements ofeach type of analysis, for example, may be performed simultaneously, oneor both measurements may be performed at one or more predetermined timesafter extinction of incident radiation bombardment onto the sample thatis being analyzed, one or both analysis may include more than onemeasurement which may be performed at one or more offset times so thatresultant radiation output decay over time may be determined and used inperforming the analysis. In some embodiments, the each of the twoanalyses may be performed independently and conclusions drawn and thencompared to determine, confirm, or fine tune the analyses. In otherembodiments, one analysis may be performed and preliminary conclusionsdrawn and then the other analysis may be performed in a manner which isbased at least in part of the results of the first analysis. In someembodiments, three step analysis (i.e. Raman, fluorescence, andphosphorescence 211) may be performed with similar variations as notedfor the two-step analysis as well as additional variations due to thepresence of further degrees of freedom associated with the existence ofthe third step or analysis type.

Both phosphorescence intensity and phosphorescence decay rate are usefulparameters in the identification of unknown materials. When one or bothare combined with measurement of Rayleigh, Raman, and/or nativefluorescence emissions, a wide range of information is made availablefor the description of the unknown chemical and materials underinvestigation.

FIG. 6C depicts examples of various types of spectral filters 112 thatmay be used in various embodiments according to the first class ofembodiments. In particular the spectral filters may be divided into twoprimary classes (1) tunable filters 214 and (2) dispersive filters 224.Tunable filters are filters that pass a given wavelength or wavelengthband depending on how they are tuned while dispersive filters pass anumber of wavelengths or wavelength bands simultaneously where energyassociated with different wavelengths is found at different anglesrelative to an incident beam that is directed onto the filter. Threeexamples of tunable filters are set forth in FIG. 6C, angle tunablefilters 215, acousto-optic tunable filters 218, and temperature tunablefilters 220. Two examples of functionality are provided for angletunable filters and temperature tunable filters: (1) monochromatorfunctionality 216 and 221, respectively, and fixed functionality 217 and222, respectively. The monochromator functionality results in theexamination of a plurality of wavelengths in a serial manner while fixedfunctionality is provided by the filter being used in single radiationpassing configuration. For the acousto-optic filter, a single,monochromator 219, functionality is exemplified. The dispersive filters,on the other hand, in combination with appropriate detector elements orarrays, may provide spectrographic functionality 227 by collecting acomplete spectrum simultaneously, scanning monochromator functionality225 or fixed monochromator functionality 226.

Raman instruments can be divided into two basic types: (1) spectrometersand (2) monochromators. Spectrometers collect complete spectrasimultaneously (using a dispersive filter element) while monochromatorscollect only one wavelength at a time. Monochromators may, e.g., usephotomultiplier tubes or avalanche photodiodes as radiation detectorsbut only to measure one wavelength or waveband at a time. Multi-channelcharge coupled devices (CCD's) may be used in spectrometers to detectmultiple wavelengths simultaneously.

Looked at in a different way, monochromators can be divided into twotypes: dispersive and non-dispersive. Dispersive monochromators employ adispersive device such as a prism or grating. Although the resolution ofa dispersive monochromator depends solely on the number of grooves inthe grating and the order of the spectrum, in practical terms theresolution depends on the focal length of the instrument. The longerfocal length instruments have higher spectral dispersion and higherresolution. Non-dispersive monochromators may use any of a variety oftunable filters including Fabry-Perot filters, thin-film dichroicinterference filters, liquid crystal tunable filters, acousto-optictunable filters, and temperature tunable filters. Tunable filters havethe advantage that they are typically wide-area devices that enable highefficiency radiation collection when used as single point detectors.

A major disadvantage of tunable filters is that they allow transmissionof only one Raman waveband at a time. Therefore, in order to measurespectra (e.g. Raman spectra) it is necessary to adjust the filter onewavelength-band at a time to collect a complete Raman spectrum.Multi-channel detectors in conjunction with dispersive filters have comeinto wide use in Raman spectroscopy because of a “multi-channeladvantage”. This advantage is due to the Raman scattered photons beingcollected simultaneously at all Raman shifts, thereby collecting allscarce Raman scattered photons resulting from a given level and durationof excitation. This advantage is especially valuable when the number ofRaman spectral resolution elements, N_(R), is large. The signal-to-noiseratio of multi-spectral-channel spectrometers is N_(R) ^(1/2) timesgreater for multi-channel instruments than for single-channelinstruments.

However, if an instrument is a dedicated quantitative analyzer thatmonitors only a few Raman lines, for example, and a complete spectrum isunnecessary, tunable filters provide several advantages. First, sincethey require no dispersion, their resolution is not limited by the sizeof the instrument. Raman analyzers using tunable filters can be madevery compact. Second, since their resolution is not restricted byentrance slit or array detector element dimensions, tunable filters havemuch larger area and higher etendue (geometrical extent), and aretherefore more efficient than spectrographs or dispersivemonochromators. This fact alone may make up for any losses due to themulti-channel advantage if the number of lines of interest is less thanabout 10. In some embodiments, beam splitting may be used to directradiation from the sample to an array of filters each having asingle-channel detector (i.e. each detector is positioned to measure aspecific shift). Such beam splitting techniques allow thesignal-to-noise advantages of multi-channel detection without the needfor collecting contiguous spectral elements as is done in amulti-channel spectrograph.

Thin film dielectric filters may be used in some embodiments as angletunable filter 215. The Military Standardization Handbook, MIL-HDBK-141,published on 5 Oct. 1962 describes in detail the history, theory andpractice of making multi-layer interference filters of a wide variety oftypes including narrow band, wide band, long pass, short pass, as wellas other filter types over a wavelength range from the ultraviolet tothe infrared. For bandpass filters the center wavelength can be adjustedby adjusting the filter angle, which is the angle between filter axisand the optical axis. This is also discussed in the book, “Thin-FilmOptical Filters” by Angus Macleod, which was most recently republishedin 1989. Both of these references are incorporated herein by reference.In some embodiments ultra-narrow band filters are used having a fullwidth at half maximum less than about ten Angstroms, more preferablyless than five angstroms, and even more preferably less than about twoangstroms.

When the filter angle is increased the center wavelength shifts towardthe blue. The amount of wavelength shift is typically 10 nm to 15 nmover an angular rotation of 30 degrees. As the filter is rotated, thefilter bandpass becomes wider and can typically double as a result of anangle change of 30 degrees. Filter wavelength change as a function ofangle was fully described in Section 20 of MIL-HDBK-141. Wavelength,λ(nm), can be converted to wavenumber, ν(cm⁻¹), since the wavenumber isthe reciprocal of wavelength:ν(cm⁻¹)=10⁷/λ(nm).

With regard to Raman analysis, the difference between the excitationfrequency of the laser and the center frequency of the filter is theRaman shift position of the filter, ν_(R). This is given by:ν_(R)=10⁷{1/λ_(L)−1/λ₀[1−(N _(a) /N*)² sin²θ]^(1/2)}where ν_(R) is the Raman shift position of the filter in wavenumbers(cm⁻¹), λ_(L) is the wavelength of the excitation radiation in nm, λ₀ isthe center wavelength of the filter at normal incidence to the opticalaxis in nm, N_(a) is the ambient index of refraction of air, N* is theeffective index of refraction of the filter materials and θ is the anglebetween the filter axis and optical axis.

Angle tunable infrared bandpass filters have been employed in Ramanspectroscopic instruments since the mid-1990s. Batchelder, et. al.employed an infrared bandpass filter with a bandpass of a fewnanometers. The 785 nm wavelength laser used for excitation in thisinstrument had an angle tuning range about 500 wavenumbers. Because ofthis limited range, a series of filters were employed, as described inU.S. Pat. No. 5,194,912, to cover a reasonable range of Raman shift. Theteachings of this patent are incorporated herein by reference.Unfortunately, bandwidth at these wavelengths typically doubles betweena filter angle of zero and about 22 degrees. At 45 degrees the filterbandpass is nearly triple the value at perpendicular incidence. Becauseof this, angle tunable filters have typically not been used much beyondan angle of 30 degrees, or so.

In the deep ultraviolet where the many advantages of Raman signalenhancement occur and background fluorescence is eliminated, the rangeof Raman shift which can be covered by angle tuning a filter isapproximately 4 times greater than in the infrared at 785 nm, going toabout 2000 wavenumbers in the UV compared to only 500 wavenumbers in theIR. This allows fewer UV filters to be used to cover a desiredwavenumber range.

Temperature tuning of the center wavelength of bandpass filter isanother alternative to angle tuning. Typical filters have a temperaturecoefficient measured in nanometers per degree Centigrade ranging fromabout 0.015 at 250 nm to about 0.020 at 800 nm. Munroe, et. al.demonstrated in 1997 that a 244 nm filter could be tuned as much as 500wavenumbers by heating the filter to 100° C. The tuning range in theinfrared is much less, being only about 22 wavenumbers at an excitationwavelength of 785 nm.

Acousto-optic tunable filters (AOTF) are especially attractive devicesfor wavelength selection in Raman analyzer instruments operated in theultraviolet. The following equation illustrates that the bandwidth ofthe filter decreases as the square of the wavelength such that at 250nm, the resolution of a 2 cm long AOTF is less than 10 wavenumbers.Added advantages of this type of tunable filter are that it is rapidlytunable from Raman band to Raman band, has no moving parts, and can begated in synchronism with pulsed ultraviolet lasers to reduce the powerconsumption and heating of the device and to provide highersignal-to-noise measurements of Raman emissions.Δλ=0.9λ₀ ² /ΔnL sin²θ_(i)where Δλ is the full width at half maximum of the bandwidth of the AOTF,λ₀, is the laser excitation wavelength, Δn is a constant property of theAOTF, L is the interaction length of the AOTF crystal, and θ_(i) is thepolarization angle of the incident Raman scattered radiation.

AOTFs are especially valuable when used in conjunction with pulsedlasers which have low operating duty cycles. Quartz is primarily used asthe AOTF media because of its transparency in the ultraviolet. Becausethe acousto-optic coefficient of quartz is low, quartz AOTFs typicallyrequire a large amount of drive power and therefore require watercooling. However, when a quartz AOTF is operated at low duty cycles aswould be desired when matched to low duty cycle pulsed lasers, theaverage power consumption becomes sufficiently low that water cooling isnot necessary. Taking advantage of this fact can lead to reduced size,reduced weight, and lower complexity analytical analysis system.

In ultraviolet based embodiments, by adjusting the temperature of afilter or angle of the filter with respect to an optical axis ofincident radiation, the center wavelength position of the filterband-pass can be changed over a wide range of Raman wave bands (e.g.shifts up to several thousand wavenumbers may be obtained using a singlefilter). This is in distinct contrast to longer wavelength systems thatrequire a plurality of filters to cover a desired Raman band ofwavelengths. This helps enable very simple and compact UV Raman point orarea sensors of wide utility.

In some, non-ultra-violet embodiments, a chemical imaging system whichemploys a liquid crystal tunable filter (LCTF) as the spectral tuningelement may be used. LCTFs do not function at deep visible orultraviolet wavelengths and are therefore not useable for imaging in theultraviolet.

FIG. 6D provides a block diagram illustrating examples of differenttypes of detectors that may be used in accordance with the first classof embodiments. A wide variety of detectors are available for use withtunable filters 112. Point detection is used when measurements areintended to be made at one point on a sample. Single channel detectorsinclude simple photodiodes 256, avalanche photodiodes 244, orphotomultipliers 236. If two-dimensional imaging of the emission of asingle line is desired, various two dimensional array detectors may beused, such as for example photomultiplier arrays 238, photodiode arrays258, CCD arrays 264, image intensified CCD (ICCD) arrays 266,electron-beam CCD (EBCCD) arrays, or electron-multiplying (EMCCD) 268.Each of these detectors is available in ultraviolet sensitive models forwhich high quantum efficiencies are available.

FIG. 6E provides a block diagram illustrating examples of differenttarget forms in which the sample may be provided.

FIG. 6F provides a block diagram illustrating examples of environmentalconditions under which sampling may be performed.

FIG. 7A provides a more detailed block diagram of components of achemical analysis system according some embodiments in the first classof analytical instrument embodiments. The block diagram of FIG. 7Ashares various components and functional relationships with those ofFIG. 6A. Elements 102, 106, 112, and 116 are common to both blockdiagrams and so are functional relationships (in terms of radiation flowbetween components) 104, 108, and 114. In addition to these commonelements and relationships, the embodiments corresponding to the blockdiagram of FIG. 7B may include (1) optional optical elements locatedalong the optical path between the laser 102 and the sample 106, (2)optional optical elements located along the optical path between thesample 106 and the spectral filter(s) 112, (3) optional optical elementslocated along the optical path between the filter(s) 112 and thedetector(s) 116, (4) a power supply or source of power (e.g. a battery)126, (5) an optional controller 128, and (6) an analyzer 122 and anoutput device 124, at least one of which is optional.

The controller 128 may include one or more input devices or componentssuch as a keyboard, a mouse, a control panel, or the like. Thecontroller may control operation of various components of the system andit may include a programmable electronic device such as a microprocessorand a memory. The controller and the analyzer may be part of the samecomponent. For example, the controller may control the powering on andoff of the radiation source and/or it may control a shutter or tuningelement to provide well controlled timing of sample irradiation andcorrelated or timed measurements for all or selected portion of there-emitted radiation (e.g. timed measurements for fluorescent andphosphorescent emission). If the optional analyzer is included in thesystem, a separate output device may not be necessary. If the optionaloutput device is included in the apparatus, the optional analyzer may beseparate from the apparatus. The optional optical elements may includemirrors, lenses, filters, splitters, apertures, and the like which maybe useful for performing a variety of functions, for example: (1)folding optical paths to reduce the size of the apparatus, (2) focusingradiation onto selected components, (3) removing undesired radiation,(4) splitting beams into multiple components, and the like.

FIG. 7B provides a block diagram illustrating various examples ofoutputs associated with some chemical analysis systems of some of theembodiments of the first class of embodiments.

In some alternatives to the embodiments of FIGS. 7A and 7B, the electronbeam pumped semiconductor laser may be replaced with an incoherentsource, such as an LED or and ELET device.

FIG. 8A provides a simplified block diagram of components of a chemicalanalysis system 400 according to a second class of embodiments of theinvention. The chemical analysis system 400 includes elements similar tothose found in the block diagram of FIG. 6A with the exception that thesemiconductor laser is replaced by a UV laser that may be asemiconductor laser or a different type of laser (e.g. a hollow cathodelaser) or even a non-coherent radiation emitting device such as an ELETdevice, and the generic spectral filter(s) of FIG. 6A are replaced byone or more tunable spectral filters 214.

FIG. 8B provides a block diagram illustrating examples of differenttypes of radiation sources that may be used in conjunction with thesecond class of embodiments. Examples of semiconductor lasers andincoherent sources have been more fully discussed herein before andexamples of hollow cathode lasers are discussed in detail in U.S. Pat.No. 6,693,944, entitled “Sputtering Metal Ion Laser” and issued to Huget al. This referenced patent is incorporated herein by reference as ifset forth in full herein.

FIG. 8C provides a block diagram illustrating examples of differenttypes of tunable filters that may be used in conjunction with the secondclass of embodiments. This figure is similar to the tunable filterportion of FIG. 6C and the reader is directed back to that discussionfor more information concerning examples of alternative filter typesthat may be used.

FIG. 11B provides a schematic illustration of a chemical analysis system400 according to some embodiments of the second class of embodiments.The system includes a package 401 which holds a UV laser radiationsource 402, a UV tunable filter 214 and a detector 416. The package 401additionally holds a multi-bounce filter 403′, a lens 403″, and aRayleigh edge filter 407. Radiation from source 402 is directed ontofilter 403′ which folds the optical path and directs the radiationthrough lens 403″ onto sample 402. Radiation coming from sample 402 ispassed back through lens 403″, passes through one element of themulti-bounce filter 403′ onto Rayleigh edge filter 407 which removes theRayleigh radiation and passes any detectable radiation of interest tothe tunable filter 214. The tunable filter 214 passes selected radiationonto detector 416 based on how it is tuned. Signals corresponding todetected radiation can be carried to an output device and/or an analyzer(which are not shown but which may be located within the package 401 orexternal to it and which may be part of the system). An analyzer maycompare information about one or more wavelengths of measured radiationto a library of information about known substances to determine whatsubstance or substances are present or alternatively to determine if aparticular substance or substances are present. The analyzer may takethe form of a programmable electronic device (e.g. a microprocessor andmemory) which may also function as a controller for the laser, thetunable filter, and the detector. In some variations of this embodiment,the package may also include an electrical power source in the form of abattery, capacitor, photocell or the like.

FIG. 9A provides a block diagram of components of a chemical analysissystem according to a third class of analytical instrument embodimentsof the invention. In the class of embodiments of FIG. 9A, multiplespectral filters are provided along with multiple detectors. Embodimentsof this class may simultaneously measure different types of spectralinformation (e.g. Raman and fluorescence as illustrated)) oralternatively, the system may be controlled to only measure one type ofspectral information (e.g. fluorescence or Raman) until a substance ofpossible interest is identified and thereafter a second type of analysis(e.g. Raman or fluorescence) may be performed to obtain furtherinformation about the substance or to further distinguish the substance.In some variations of the embodiments of this class, prior to performingsecondary analysis (e.g. Raman analysis) a sample may be concentrated(e.g. positive detections from a one or a plurality of successiveprimary analyses may be used to cause (e.g. via blowing, sucking, orelectrostatic attraction) such samples (e.g. air born or liquid bornparticles) to move into a trap so as to increase concentration forsubsequent analysis by the secondary analysis technique.

The system of FIG. 9A provides a package 501 in which a radiation source502 is located along with a Raman detector 516-1 and a fluorescencedetector 516-2 and at least two spectral filters 214-1 and 214-2 forrespectively directing 1^(st) and 2^(nd) selected radiations on todetectors 516-1 and 516-2. The package may also include filter 503-1 andfilter or mirror 503-2, Rayleigh detector 503-3, power supply 526,controller 528, and analyzer 522 and/or output device 524. The packagemay also include a stepper motor, linear motor, or other electronic orelectromechanical devices for tuning any tunable filters that arepresent.

In the chemical analysis method involving the device of FIG. 9A,radiation is directed from the radiation source 502 to sample 506.Return radiation is directed onto filter 503-2 where Rayleigh radiationis reflected toward filter or mirror 503-1 of which a portion may bedirected to Rayleigh detector 503-3. Radiation of detection interest ispassed by filter 503-2 and encounters filter 214-1 which reflects 1^(st)selected radiation to the Raman detector 516-1 and transmits otherradiation of detection interest onto filter 214-2. Filter 214-2 reflects2^(nd) selected radiation onto fluorescence detector 516-2 and maytransmit or absorb other wavelengths that are not of interest. In somealternative embodiments, if only 2^(nd) selected radiation istransmitted by filter 214-1 the second filter 214-2 may not benecessary. Signals from detectors 516-1 and 516-2 are sent to Analyzer522 directly or via an output device 524, e.g. in those embodimentswhere the analyzer does not form part of the instrument. Based on theresults produced by analyzer 522, the controller 528 may implementdifferent method options (e.g. programmed routines).

In some alternative embodiments, the fluorescence detection of theexample of FIG. 9A may be replaced with phosphorescence detection sothat a combination of phosphorescence and Raman detection is provided.In still other embodiments, the Raman detection may be replaced withphosphorescence detection such that combined phosphorescence andfluorescence analysis is provided. In case of either phosphorescence orfluorescence, the measurements may be made during irradiation of thesample or at one or more times after irradiation. The timing ofirradiation and measurement, as well as analysis, may be performed bythe controller and/or may be controlled by an external device thatcommunicates with the controller. In embodiments where phosphorescenceor fluorescence is measured after irradiation is stopped, it may bepossible to eliminate one or more of the filters shown in FIG. 9A.

When fluorescence is measured, it may be desirable to make one or moremeasurements in the range of 0.1 nS to 100 nS after extinguishing theapplication of excitation radiation to the sample so as to cover decaytimes that may be typical for the substances of interest. Whenphosphorescence is measured, it may be desirable to make a plurality ofmeasurements over a period in the range of 0.5 mS to 0.5 S afterextinguishing the application of excitation radiation so as to coverdecay times that may be typical for the substances of interest. In someembodiments, the fluorescence detection and phosphorescence detectionmay use a common detector, or set of detectors, and a common spectralfilter, or set of filters. Of course in some embodiments repeatedmeasurements of fluorescence or phosphorescence may occur over longerranges or shorter ranges of time and may even occur during sampleirradiation. In some embodiments, it may be useful in helping todistinguish fluorescence emission from phosphorescence emission by notonly measuring appropriate spectral amounts during emission decay (i.e.after extinguishing excitation radiation) but also to make one or moretimed measurements after initially applying excitation radiation to thesample so as to determine emission build up profiles as well.

In some embodiments, the spectral filters 214-1 and 214-2 may scanthrough a plurality of different wavelengths so that differentwavelength ranges are allowed to reach their respective detectors atdifferent times. As another example, in some other embodiments one ormore additional spectral filters may be located between the primaryfilters 214-1 and 214-2 and their respective detectors to provide adesired level of wavelength specificity. As a further example, in stillother embodiments additional spectral selectively may be built into thedetector components themselves.

FIG. 9B provides a block diagram of components of a chemical analysissystem according to a fourth class of analytical instrument embodimentsof the invention. The system of FIG. 9B allows multiple Ramanwavelengths (λ₁, λ₂, . . . , λ_(N)) of interest to be simultaneouslydetected. The components of FIG. 9B are similar to those of FIG. 9A withthe exception that extra spectral filters up to 214-N and detectors upto 516-N are included and where each of the filters 214-1 to 214-N aretailored to pass to detectors 516-1 to 516-N selected bands of Ramanwavelengths of interest. In some alternative embodiments, the multipleRaman detectors and spectral filters may be replaced or supplemented byfluorescence and/or phosphorescence detectors and filters to providemultiple simultaneously detected bands of Raman, fluorescence and/orphosphorescence data.

FIG. 9C provides a block diagram of components of a chemical analysissystem according to a fifth class of analytical instrument embodimentsof the invention. The system of FIG. 9C has many elements in common withthat of FIG. 9A and as such these elements are marked with the samereference numerals as those of FIG. 9A. The embodiment of FIG. 9C addsphosphorescence as an additional detection system or analysis methodcompared to that of FIG. 9A. In this embodiment, the fluorescence filter214-2 and detector 516-2 and phosphorescence filter 214-3 and detector516-3 are shown as being separate though in other embodiments they maybe shared since fluorescence and phosphorescence emission bandstypically largely overlap and thus could also use the same spectralfilters and detectors particularly since these two types of emission aretypically differentiated by decay times that differ by one or moreorders of magnitude. Fluorescence decay times are typically in the 100pS to 10 nS range and phosphorescence decay times are in the 0.5 mS to100 mS range. These decay rates may allow useful measurements to be madefor these emission types during different time periods, e.g. during atime range of 100 pS to 100 nS for fluorescence and during a range of0.5 mS to 1000 mS for phosphorescence (as measured from the extinctionof the excitation radiation). The use of separate fluorescence andphosphorescence detectors or at least additional phosphorescencedetectors, as shown in FIG. 9C, may be warranted since phosphorescenceoften extends to longer wavelengths than fluorescence.

The radiation source 502 in FIG. 9C is also explicitly shown asoptionally including an output modulator (e.g. an acousto-opticmodulator) that may be used to precisely control excitation radiationregardless of laser radiation build up or decay time. In otherembodiments there may not be a need for such an independent modulator.For example, in some embodiments, the laser or other optical source mayhave a sufficiently fast response time to eliminate the need for anindependent modulator. In some embodiments, one or more of the filterelements may provide appropriate modulation. In some uses of the systemof FIG. 9C, one or more of the detector systems may be disabled. In someembodiments, Raman detection may occur during a period of irradiationwhile one or both of fluorescence and phosphorescence detection mayoccur at one or more times (e.g. in whole or in part, after irradiationhas ceased) and fluorescence and/or phosphorescence emission radiationfor different wavelengths and different times may be determined. In someembodiments, one or more of the detection methods may be used initiallyand followed by one or more of the other detection methods. Such followup detection may be based in whole or in part on a preliminary analysisof the results of the initial detection and may provide confirmation ofdetected or non-detected substances or may provide further specificityconcerning potentially present substances.

Various alternatives to the embodiment of FIG. 9C exists. In one suchembodiment, the Raman spectral filter may be used to provide differentwavelengths to the Raman detector as the sample is being irradiatedwhile the tunable filters 214-2 and 214-3 could both be used to directdifferent wavelengths of emission radiation onto detectors 516-2 and516-3 at the same time for simultaneous fluorescence spectral detectionand at a later time for simultaneous phosphorescence detection. In stillother embodiments, additional combined fluorescence and phosphorescencefilters and detectors may be provided to allow for additionalsimultaneous spectral detection at different wavelengths.

FIG. 10A provides a block diagram of a chemical analyzer package orinstrument according to some embodiments of the invention where thepackage includes a power supply and a controller.

FIG. 10B provides a block diagram of a chemical analyzer packageaccording to some embodiments of the invention where the packageincludes an output device while a power supply and/or analyzer may beseparate from the package.

FIG. 10C provides a block diagram illustrating some preferentialvolumes, weights, and power consumption levels associated with a compactchemical analyzer package according to some embodiments of theinvention. Of course in other embodiments, other instruments havingother volumes, weight, and power consumption are possible.

Analytical instruments in the context of the present application referto instruments that analyze a sample of material by exposing thatmaterial to a radiation and then detecting selected radiation, current,or voltage resulting from the interaction between the incident radiationand the sample. Some preferred systems also include a computer andappropriate software to aid in the analysis. Sample analyticalinstruments include Raman spectroscopy systems, UV resonance Ramanspectroscopy systems, electrophoresis systems (e.g. gel plane orcapillary type), and high performance liquid chromatography systems. Thesamples to be analyzed may be labeled or non-labeled. The samples may beof DNA or molecular or chemical structures.

FIG. 12 illustrates the elements of a capillary electrophoresisinstrument with a laser induced fluorescence detector. A laser outputbeam from a laser 600 (e.g. a semiconductor laser or sputtering metalion hollow cathode laser) is incident on a sample of material 602 insidecapillary 630. The sample of material has been separated or segregatedfrom a sample source 602′ by the process of electrophoresis and dumpedinto reservoir 628. Power supply 618 provides the high voltage, lowcurrent needed to drive the electrophoretic separation process. Theseparated material 602 fluoresces when excited by the laser radiationdue to absorption by natural or labeling fluorophors within the sample.The fluorescence light is collected by lens 620, passed through filter622 which blocks Rayleigh scattered light at the laser wavelength, andis collected by detector 624 and processed by computer 626. Variationsof this optical detection method might use a semiconductor laser orhollow cathode laser in conjunction with a refractive index detector orRaman spectroscopic detector (including, e.g. a UV tunable filter). Theelectrophoretic separation can be done in a capillary or in a planargel, which is in common use. The system may also include one or morewavelength blocking elements (e.g. tunable filters) for separating oneor more bands of fluorescence emission wavelengths excited in a sampleby the incident radiation.

FIG. 13 illustrates the elements of a liquid chromatography instrumentwith a laser induced fluorescence detector. A laser output beam from,e.g. a semiconductor laser or sputtering metal ion hollow cathode laser600 is incident on a sample of material 602 within capillary 630′ whichhas been separated or segregated from a sample source 602″ by theprocess of liquid chromatography and dumped into reservoir 628. Theseparation process is driven by pressure supplied by pump 632. Theseparated material 602 fluoresces when excited by the laser radiationdue to absorption in natural or labeling fluorophors within the sample.The fluorescence radiation is collected by lens 620, passed throughfilter 622 which blocks Rayleigh scattered light at the laserwavelength, is collected by detector 624 and processed by computer 626.Other variations of this optical detection method may use, e.g., asemiconductor laser or sputtering metal ion hollow cathode laser inconjunction with a refractive index detector or Raman spectroscopicdetector (e.g. including a tunable filter).

The use of semiconductor lasers (e.g. electron beam pumped semiconductorlasers or sputtering metal ion hollow cathode lasers in the aboveapplications greatly simplifies these types of instruments. Use oftunable filters in combination with these lasers in some embodiments mayalso result in simplification of analytic instruments, size and weightreductions, improved reliability, and/or decreased power consumption.

This application incorporates herein by reference the teachings of U.S.patent application Ser. No. 11/245,418, filed Oct. 5, 2005 which isentitled “Electron Beam Pumped Semiconductor Laser” and was filed by Huget al.

In view of the teachings herein, many further embodiments, alternativesin design and uses of the instant invention will be apparent to those ofskill in the art. As such, it is not intended that the invention belimited to the particular illustrative embodiments, alternatives, anduses described above but instead that it be solely limited by the claimspresented hereafter.

We claim:
 1. An apparatus for providing chemical analysis, comprising:a) a package; b) a source of excitation radiation located within thepackage, configured to direct excitation radiation onto a samplelocation that is external to the package, wherein the excitationradiation has a wavelength less than 300 nm; c) at least one opticalelement configured to receive emission radiation coming from the samplelocation, wherein the emission radiation arises from the excitationradiation, and wherein the at least one optical element within thepackage directs the emission radiation along at least one detection pathwithin the package; d) at least one detector within the package todetect the emission radiation at at least one location along thedetection path; e) at least one controller configured to controloperation of the source, and the detector, and f) at least one analyzerconfigured to determine whether the detected emission radiationcorresponds to a chemical compound of interest, wherein the controllerand analyzer are selected from the group consisting of: (1) multipleelectronic components, (2) a single electronic component that providesboth control and analysis, (3) multiple programmable electroniccomponents, and (4) a single programmable electron component and whereinsource and controller are configured to provide pulses of excitationradiation and wherein the at least one detector and controller areconfigured to make a plurality of temporally spaced detections in amanner synchronized with the timing of the pulses of excitationradiation.
 2. The apparatus of claim 1 wherein the controller, the atleast one detector, and the source are configured to provide fordetection of emission radiation between pulses of applied excitationradiation.
 3. The apparatus of claim 1 wherein the controller, the atleast one detector and the source are configured to provide fordetection of emission radiation during pulses of excitation radiationfrom the source.
 4. The apparatus of claim 1 wherein the controller, theat least one detector and the source are configured to provide aplurality of detection of emission radiation between two consecutivepulses of excitation radiation from the source wherein the detectionsare provided with a relative timing selected from the group consistingof: (1) relative to the initiation of a pulse and (2) relative to thetermination of each pulse.
 5. The apparatus of claim 1 wherein thesource comprises a device selected from the group consisting of: (1) ahollow cathode laser; (2) an LED, (3) an LET, (4) a semiconductor laser,and (5) an e-beam pumped semiconductor laser.
 6. The apparatus of claim1 wherein the source provides excitation radiation at a wavelength lessthan 280 nm.
 7. The apparatus of claim 1 wherein the source providesexcitation radiation at a wavelength less than 250 nm.
 8. The apparatusof claim 1 additionally comprising a battery located within the packagefor powering the source, the detector, the at least one controller, andthe at least one analyzer.
 9. The apparatus of claim 1 wherein theemission radiation comprises native fluorescence emission radiation. 10.The apparatus of claim 1 wherein the emission radiation is selected fromthe group consisting of: (1) native fluorescence emission radiation, (2)Raman emission radiation, (3) phosphorescence emission radiation, (4)Rayleigh scattering, and (5) luminescence emission radiation.
 11. Theapparatus of claim 1 wherein the emission radiation is selected from thegroup consisting of at least two of: (1) native fluorescence emissionradiation, (2) Raman emission radiation, (3) phosphorescence emissionradiation, and (4) Rayleigh scattering.
 12. The apparatus of claim 1wherein the at least one detector comprises a plurality of detectorsthat receive the emission radiation from the sample location without useof a dispersive optical element.
 13. The apparatus of claim 1 whereinthe at least one detector comprises a plurality of detectors thatreceive the emission radiation from the sample location using a tunableoptical element.
 14. The apparatus of claim 1 wherein the samplelocation comprising a manufacturing surface.
 15. The apparatus of claim1 wherein the manufacturing surface comprises a surface inpharmaceutical manufacturing.
 16. The apparatus of claim 1 wherein themanufacturing surface comprises a surface in food manufacturing.